Gilbert syndrome is a common inherited condition that affects how the liver processes bilirubin. Many living with Gilbert syndrome have no daily problems, but some notice mild yellowing of the eyes or skin, especially during illness, stress, fasting, or dehydration. The signs of Gilbert syndrome often first show up in the teen years or early adulthood, and the pattern is usually lifelong. Not everyone will have the same experience. Gilbert syndrome does not usually shorten life, and most people need no treatment other than avoiding triggers when possible and checking with a doctor if jaundice is new or worsening.
How many people live with Gilbert syndrome?
Worldwide, Gilbert syndrome is estimated to affect about 4% to 16% of people, or roughly 330 million to 1.3 billion people, and the range is wide because rates differ by ancestry and by how studies look for the condition (StatPearls, 2023). In the United States, about 3% to 7% of people are thought to have it, which works out to roughly 10 million to 24 million people (MedlinePlus Genetics, 2021).
Overview
Gilbert syndromeSymptoms
Gilbert syndrome often causes no symptoms. When signs do appear, they usually include mild yellowing of the eyes or skin, sometimes with tiredness or stomach discomfort.
Outlook and prognosis
People with Gilbert syndrome usually have a normal life expectancy and stay healthy. Mild yellowing can come and go, often during fasting, illness, stress, or dehydration, but it does not damage the liver.
Causes and risk factors
Gilbert syndrome is caused by an inherited change in the UGT1A1 gene, sometimes arising new. Family history raises the chance. Fasting, illness, stress, hard exercise, dehydration, and lack of sleep can make it more noticeable.
Genetic influences
Genetics are central to Gilbert syndrome. It is usually caused by inherited changes in the UGT1A1 gene, and these genetic variations largely determine who develops it, though symptoms and bilirubin levels can vary from person to person.
Diagnosis
Gilbert syndrome is usually diagnosed from a typical pattern on blood tests, especially mildly raised bilirubin with otherwise normal liver results. Doctors may also consider clinical features. Genetic tests are sometimes used to confirm the diagnosis of Gilbert syndrome.
Treatment and drugs
Gilbert syndrome usually needs no medicine. Care focuses on avoiding common triggers such as fasting, dehydration, illness, and lack of sleep, which can raise bilirubin and briefly yellow the eyes or skin. New or worsening symptoms need medical review.
Symptoms
Many people with Gilbert syndrome feel completely well most of the time and may only hear about it after routine blood work or a brief yellow tinge in the eyes. For many, the early features of Gilbert syndrome are easy to miss because they tend to come and go rather than stay constant. Features can vary from person to person and may become more noticeable at certain times. Gilbert syndrome does not usually cause ongoing liver damage.
Many people with Gilbert syndrome have no day-to-day problems at all. It is often found by chance when a blood test shows a mild rise in bilirubin.
The most noticeable sign is a yellow tint in the whites of the eyes, and sometimes the skin. This can be subtle, so people may first spot it in bright bathroom light or in photos.
Yellowing is more likely during fasting, dehydration, illness, hard exercise, stress, or after poor sleep. For many, this means the color change appears for a few days and then fades once the trigger passes.
Some people living with Gilbert syndrome report feeling tired, run-down, or less energetic during episodes. These feelings are not specific to Gilbert syndrome, so they can overlap with stress, poor sleep, or a short-term illness.
How people usually first notice Gilbert syndrome?
How Gilbert syndrome is first noticed is often surprisingly subtle: many people first learn they have it in the teen years or early adulthood after mild yellowing of the eyes or skin appears during stress, illness, fasting, dehydration, hard exercise, or lack of sleep. Some may also notice dark urine, tiredness, or mild belly discomfort, but many living with Gilbert syndrome feel completely well and only find out after a routine blood test shows a slightly higher bilirubin level, a yellow pigment made when the body breaks down old red blood cells. In most cases, the first signs of Gilbert syndrome come and go rather than steadily worsening, which is one reason it can be missed for years before a doctor connects the pattern.
Types of Gilbert syndrome
No distinct types of Gilbert syndrome are widely recognized.
Can I slow down the onset of symptoms?
Not really—because Gilbert syndrome is inherited, there is no proven way to meaningfully delay when it starts, and no lifestyle change has been shown to prevent the condition. What may help is lowering the chance of flare-ups once you have it: staying well hydrated, eating regularly instead of fasting or skipping meals, getting enough sleep, managing stress, and avoiding very hard physical strain are all linked to fewer episodes of yellowing of the eyes or skin in many people. There are no standard preventive medicines for Gilbert syndrome, but it is usually harmless, and learning your own triggers can often help you feel more in control.
What genetics can tell you about symptoms
For most people with Gilbert syndrome, genetics can tell you that the condition is caused by an inherited change that slows how the liver processes bilirubin, which is why mild jaundice, especially yellowing of the eyes, is the main symptom. Genetic differences can influence how high bilirubin levels run and how often symptoms show up, so some people notice almost nothing while others have more visible yellowing during stress, illness, fasting, hard exercise, or lack of sleep. Symptoms often begin in the teen years or early adulthood, but the genetic result does not usually predict day-to-day symptoms with great precision.
Causes and risk factors
Many people with Gilbert syndrome only notice a mild yellow tinge in the eyes after a missed meal, poor sleep, or a minor illness. Gilbert syndrome is usually caused by an inherited change in the UGT1A1 gene, which makes it harder for the liver to clear bilirubin. Genes set the stage, but environment and lifestyle often decide how the story unfolds. This helps explain what causes Gilbert syndrome symptoms to show up from time to time, including fasting, dehydration, stress, hard exercise, infections, and sometimes menstruation. A family history raises the chance of Gilbert syndrome, and it is often first noticed in the teen years or early adulthood.
What are the most common causes or risk factors?
The main cause of Gilbert syndrome is an inherited gene change that makes the liver a bit slower at clearing bilirubin, a yellow waste substance made when old red blood cells are broken down. The biggest risk factor is having a family history of the condition, and it is often first noticed in the teen years or early adulthood. Many living with Gilbert syndrome find that yellowing of the eyes or skin is more likely to show up during fasting or skipping meals, dehydration, illness, stress, hard exercise, lack of sleep, or around a menstrual period.
Environmental and biological risk factors
If you are wondering about Gilbert syndrome risk factors, the list is short. Doctors often group risks into internal (biological) and external (environmental). For Gilbert syndrome, clear environmental causes have not been shown, and only a few biological factors are linked with it being noticed more often.
Gilbert syndrome is identified more often in males than in females. This difference is thought to be related in part to hormone effects on bilirubin levels.
Many people with Gilbert syndrome first have abnormal bilirubin results in the teen years or early adulthood. Hormonal changes around puberty can make the pattern easier to notice.
Body-based conditions that increase the breakdown of red blood cells can make Gilbert syndrome more likely to come to attention. When the body makes more bilirubin than usual, the underlying tendency is easier to detect.
No specific environmental exposure has been proven to cause Gilbert syndrome. For many, this can mean that pollution, chemicals, or infections are not considered established causes of the condition.
Genetic risk factors
A tendency for mild yellowing of the eyes or higher bilirubin on blood tests often starts with an inherited difference in how the liver handles bilirubin. In Gilbert syndrome, the key gene involved is UGT1A1, which makes an enzyme that helps clear bilirubin from the body. People with the same risk factor can have very different experiences. The strongest inherited risk is usually having lower-working versions of this gene passed down in a family.
UGT1A1 gene: Gilbert syndrome is usually caused by an inherited change in the UGT1A1 gene. This gene helps the liver turn bilirubin into a form the body can remove.
TA repeat: The most common variant adds an extra TA repeat in the gene's control region, the stretch that helps set how active the gene is. That lowered output is one of the main genetic causes of Gilbert syndrome.
Two gene copies: Risk is highest when a lower-working UGT1A1 variant is inherited from both parents. In many families, this leads to a mild but lifelong tendency toward higher bilirubin. Carrying a genetic change doesn't guarantee the condition will appear, because the effect can be mild and varies from person to person.
Family history: Gilbert syndrome often runs in families because the same UGT1A1 variants can be passed down across generations. Having a parent, sibling, or child with the condition raises the chance of sharing the same inherited trait.
Ancestry background: The frequency of UGT1A1 variants is not the same in all populations, so inherited risk can differ by ancestry. This helps explain why some gene patterns are more common in certain families or regions.
Other variants: Some people have other mild changes in UGT1A1 instead of, or along with, the common TA repeat. These variants also reduce bilirubin processing, and the exact change can vary by family background.
Lifestyle risk factors
Gilbert syndrome is inherited, so lifestyle habits do not cause it. However, how lifestyle affects Gilbert syndrome can be noticeable because certain habits can trigger temporary rises in bilirubin and make jaundice, fatigue, or malaise more likely. The main lifestyle-related issues are patterns that stress the body, especially around food intake, fluids, exertion, alcohol, sleep, and stress.
Fasting, meal skipping, and very low-calorie dieting can raise bilirubin levels in people with Gilbert syndrome. This can make yellowing of the eyes or skin more likely during those periods.
Rapid weight-loss plans can put metabolic stress on the body and trigger bilirubin spikes. Slower, steadier weight management is usually less likely to worsen Gilbert syndrome symptoms.
Dehydration can concentrate the blood and make bilirubin elevations more noticeable in Gilbert syndrome. Drinking enough fluid may help reduce symptom flare-ups, especially in hot weather or during exercise.
Very strenuous or prolonged exercise can act as a physical stressor and sometimes bring on jaundice or fatigue in Gilbert syndrome. Moderate activity is often better tolerated than sudden extreme training loads.
Risk prevention
Gilbert syndrome cannot usually be prevented because it is an inherited condition, but many people can lower the chance of yellowing episodes and other symptoms by avoiding common triggers. For many living with Gilbert syndrome, this often means planning around fasting, dehydration, illness, and heavy physical stress. Prevention is flexible—it adapts to your life and health background. Knowing the common Gilbert syndrome jaundice triggers can make day-to-day symptoms easier to manage.
Skipping meals, crash dieting, and fasting can raise bilirubin levels and trigger jaundice in people with Gilbert syndrome. Eating regularly and avoiding very low-calorie plans may help keep symptoms steadier.
Dehydration can make Gilbert syndrome symptoms more noticeable, especially during hot weather, travel, vomiting, or diarrhea. Drinking enough fluids through the day helps reduce that stress on the body.
Infections such as colds, flu, or stomach bugs can bring on temporary yellowing of the eyes or skin. Rest, fluids, and early medical care when you are unwell may help limit Gilbert syndrome flare-ups.
Very intense exercise without enough recovery can trigger symptoms in some people with Gilbert syndrome. Steady activity, good hydration, and enough fuel before and after workouts are often better tolerated.
Can you prevent Gilbert syndrome?
No, Gilbert syndrome itself cannot be prevented because it is an inherited condition that you are born with. But many people can lower the chance of flare-ups, especially yellowing of the eyes or skin, by avoiding common triggers such as skipping meals or fasting, dehydration, and extreme physical stress. Getting enough sleep and managing illnesses promptly may also help, although symptoms can still come and go.
Transmission
Gilbert syndrome is not infectious, so you cannot catch it from someone through kissing, sharing food, sex, blood, or everyday contact. Instead, Gilbert syndrome is an inherited condition that affects how the liver processes bilirubin, and for many families, how Gilbert syndrome is inherited means a child receives the related gene change from both parents.
Many people with Gilbert syndrome inherit one changed copy from each parent, although the pattern can vary and some relatives may never know they carry it. If Gilbert syndrome runs in your family, the tendency can be passed from parent to child, but not every child will necessarily have the same findings.
When to test your genes
Genetic testing for Gilbert syndrome is usually not needed if the pattern is typical: mild, repeated unconjugated bilirubin elevation with otherwise normal liver tests. It can help when the diagnosis is unclear or before medicines such as irinotecan or atazanavir, because UGT1A1 changes can raise the risk of side effects.
Diagnosis
Gilbert syndrome is often found after a blood test shows mildly higher bilirubin, especially during stress, illness, fasting, or after hard exercise. Many living with Gilbert syndrome feel well, but some notice brief yellowing of the eyes that comes and goes. Doctors usually begin with simple blood tests, and the diagnosis of Gilbert syndrome is often made by the pattern of results rather than one single test.
A clinician asks about episodes of yellowing, recent illness, fasting, exercise, alcohol use, and medicines that can affect bilirubin levels. A detailed family and health history can help show whether the pattern fits Gilbert syndrome rather than another liver problem.
Blood tests usually show a mild rise in total bilirubin, mainly the unconjugated type, while other liver results stay normal. This pattern is a key part of the diagnosis of Gilbert syndrome, especially when it has been seen more than once.
Tests such as AST, ALT, alkaline phosphatase, and albumin are usually normal in people with Gilbert syndrome. Normal results make ongoing liver damage less likely and help point away from hepatitis or blocked bile flow.
Doctors may also check a complete blood count, reticulocyte count, and markers of red blood cell breakdown if needed. These tests help rule out hemolysis, which can also cause unconjugated bilirubin to rise.
How is Gilbert syndrome diagnosed?
Gilbert syndrome is usually diagnosed with a review of symptoms, a physical exam, and simple blood tests that show a mild rise in bilirubin, a yellow substance in the blood, while other liver tests stay normal and there are no signs of another liver or blood problem. Doctors may repeat the blood test at another time, since bilirubin levels often go up and down and may rise during illness, stress, fasting, or not getting enough sleep. A genetic test can sometimes help if the cause is still unclear, but most people do not need one.
Stages of Gilbert syndrome
Gilbert syndrome does not have defined progression stages. That is because it is a lifelong inherited tendency to have mild ups and downs in bilirubin levels rather than a condition that steadily worsens over time. Gilbert syndrome is usually recognized when a blood test shows mildly raised bilirubin, often during routine care or while checking another issue, and liver tests are otherwise normal. Many people feel relief once they understand what’s happening, and Gilbert syndrome diagnosis may also include a review of symptoms, medicines, and sometimes family history to rule out other causes of jaundice.
Outlook and prognosis
The outlook for people with Gilbert syndrome is excellent, and life expectancy is normal. It is a benign, lifelong condition that may cause intermittent mild jaundice, especially during fasting, illness, stress, dehydration, or strenuous exercise, but it does not lead to liver damage, cirrhosis, or liver failure. Most people do not need treatment, and symptoms, if present, are usually mild and manageable by avoiding common triggers when possible. Mortality is not increased by Gilbert syndrome itself. A practical exception is that some individuals may have a higher risk of side effects from certain medications that rely on bilirubin-processing pathways, so clinicians may consider this when prescribing.
Long-term effects
For most people, Gilbert syndrome has a very mild long-term outlook and does not damage the liver. Bilirubin levels can rise and fall over time, so some may notice occasional yellowing of the eyes or skin during illness, fasting, stress, or heavy exercise. It is important to remember that long-term does not always mean progressive. When people ask about the long-term effects of Gilbert syndrome, the main point is that it is usually a lifelong but harmless pattern rather than a disease that worsens.
The most common long-term feature is recurring mild jaundice, especially yellowing in the whites of the eyes. These episodes often come and go rather than staying constant, and they may be more noticeable at certain times of life.
Gilbert syndrome does not usually lead to cirrhosis, liver failure, or ongoing liver injury. For many living with Gilbert syndrome, life expectancy is normal and overall liver function stays normal.
Blood bilirubin often remains mildly higher than average over many years. Many people notice small adjustments like looking more yellow during a fever, after missing meals, or after strenuous activity, then returning to their usual appearance.
Some people with Gilbert syndrome process certain medicines more slowly, which can raise the chance of side effects. This matters most with a small number of drugs rather than everyday medicines in general.
How is it to live with Gilbert syndrome?
Living with Gilbert syndrome is usually more of an occasional nuisance than a serious illness, because most people feel well most of the time and have a normal life span. Some may notice brief episodes of yellowing of the eyes or skin, tiredness, or feeling run-down, often during stress, illness, fasting, dehydration, hard exercise, or lack of sleep, so daily life may sometimes involve paying closer attention to meals, fluids, and rest. For people around you, the main effect is often concern when jaundice appears unexpectedly, but it can help to know that Gilbert syndrome is a common, harmless difference in how the liver processes bilirubin and usually does not lead to liver damage.
Treatment and drugs
Gilbert syndrome usually does not need treatment, because it is a harmless inherited condition that causes mild rises in bilirubin, the yellow pigment that can tint the skin or eyes. For many people, treatment begins with small daily steps, such as avoiding long fasts, staying well hydrated, getting enough sleep, and managing stress, since these can help reduce flare-ups. There is no routine medicine for Gilbert syndrome, and most people live normal, healthy lives without drugs. It is still important to tell your doctor or pharmacist that you have Gilbert syndrome, because a few medicines are processed differently and may cause more side effects. If the early symptoms of Gilbert syndrome seem to be getting worse, or yellowing lasts longer than usual, your doctor may check for another cause rather than blaming Gilbert syndrome alone.
Can you cure Gilbert syndrome?
No, Gilbert syndrome cannot be cured, but it is a mild inherited condition that usually does not need treatment. If it causes brief episodes of yellowing in the eyes or skin, these often pass on their own, and simple steps like staying well hydrated, eating regular meals, and avoiding long periods without food can help reduce flare-ups.
Non-drug treatment
Most people living with Gilbert syndrome do not need medical treatment, but day-to-day habits can help keep bilirubin levels steadier and make flare-ups less likely. Jaundice often shows up during common stressors such as skipping meals, being dehydrated, recovering from an illness, or pushing through several nights of poor sleep. Managing this condition often means focusing on regular routines and avoiding triggers rather than adding special therapies.
Eating on a steady schedule can help prevent bilirubin from rising. Long gaps without food, fasting, and crash diets are common triggers for yellowing of the eyes or skin in Gilbert syndrome.
Drinking enough fluids may lower the chance of flare-ups, especially during hot weather, exercise, vomiting, or diarrhea. Some may find their symptoms are more noticeable when they are run down and dehydrated.
Poor sleep and emotional or physical stress can trigger episodes in many people with Gilbert syndrome. Simple routines—like keeping a regular bedtime or building in short recovery breaks—can have lasting benefits.
Exercise is usually healthy, but very intense training without enough rest, food, or fluids can bring on jaundice. A balanced routine with recovery days may be more helpful than sudden bursts of hard effort.
Your genes may have an impact on how drugs work for you
People with Gilbert syndrome process bilirubin, a yellow waste product, a bit more slowly, and that same body pathway also helps handle some medicines, so certain drugs can build up more than expected or make jaundice more noticeable. A well-known example is the cancer drug irinotecan, which can cause stronger side effects in some people with Gilbert syndrome, and a few other medicines may also be harder for the body to clear. This kind of gene-based difference in how the body handles medicine is part of pharmacogenomics, and it is worth mentioning to your doctor or pharmacist so they can choose the safest option and watch for problems.
Pharmacological treatments
Most people with Gilbert syndrome do not need medicine, because it is usually a mild condition that comes and goes. For many, treatment for Gilbert syndrome is mainly about avoiding common triggers such as fasting, dehydration, illness, and too little sleep. In rare situations, a doctor may consider medicine to lower bilirubin for a short time, but this is not standard care.
There is no approved everyday medication for Gilbert syndrome, and most people do well without one. If jaundice appears during stress, a stomach bug, or skipped meals, the focus is usually on fluids, regular eating, and rest rather than starting a drug.
Phenobarbital can lower bilirubin levels and may reduce yellowing of the eyes or skin for a time. It is rarely used because Gilbert syndrome is usually harmless, and this medicine can cause sleepiness, drug interactions, and other side effects.
Gilbert syndrome can affect how the body handles certain medicines, so treatment plans may need extra care even though the syndrome itself usually does not need drugs. Important examples include irinotecan, atazanavir, and indinavir, which can lead to stronger side effects or more noticeable jaundice in some people.
Genetic influences
Gilbert syndrome often comes to light when mild yellowing of the eyes seems to show up in more than one relative, especially during illness, stress, or fasting. It is usually caused by inherited changes in the UGT1A1 gene, which helps the liver clear bilirubin, the yellow pigment made when red blood cells break down. Gilbert syndrome is most often passed down in an autosomal recessive pattern, so people typically inherit a lower-working copy of this gene from each parent, while parents with one copy may have no symptoms or only very mild changes. The exact UGT1A1 variant can differ across families and ancestry groups, but the overall effect is similar: bilirubin is processed more slowly than usual. Even with the same gene change, people can have very different bilirubin levels and may notice symptoms only from time to time. This helps explain why early symptoms of Gilbert syndrome can be so mild that the condition is found only after routine blood tests or a brief episode of jaundice.
Is Gilbert syndrome genetic?
Genetics are central to Gilbert syndrome. It is usually caused by inherited changes in the UGT1A1 gene, and these genetic variations largely determine who develops it, though symptoms and bilirubin levels can vary from person to person.
Having a genetic risk is not necessarily a diagnosis
Genetic variants, which are differences in genes, are a normal part of human biology and are common across the general population. Most of these variants do not directly affect health and simply reflect natural human diversity. For many genes, carrying a variant connected to a condition suggests a possible link rather than a certain diagnosis, especially when several genes and environmental factors are involved. In some cases, though, a single well-understood variant in a specific gene is enough to confirm a diagnosis.
Pharmacogenetics—how genetics influence drug effects
For many people with Gilbert syndrome, day-to-day care is simple and no regular treatment is needed, but genetics can matter when a new medication is being considered. Gilbert syndrome is usually linked to changes in a gene called UGT1A1, which helps the liver handle bilirubin and also helps process some drugs. Not every difference in response is genetic, but this gene change can raise the risk of side effects from certain medicines, especially the cancer drug irinotecan and some HIV medicines such as atazanavir. In those situations, doctors may use genetic test results to choose a lower dose, pick a different medicine, or monitor more closely. This is one reason why questions about medications to avoid with Gilbert syndrome are worth discussing before starting treatment, even if symptoms are usually mild. Many living with Gilbert syndrome can safely take most common medicines, but it helps to tell your care team about the condition so drug choices can be made with that gene pattern in mind.
Interactions with other conditions
People with Gilbert syndrome often notice that mild yellowing of the eyes is more likely to show up when the body is under strain, such as during a viral illness, after not eating enough, or when another health problem is active. Gilbert syndrome itself is usually harmless and does not damage the liver, but it can make bilirubin blood tests harder to interpret if you also have hepatitis, fatty liver disease, or another liver condition. Having more than one diagnosis can make symptoms feel harder to untangle, because jaundice from Gilbert syndrome is mild, while jaundice from liver disease is often stronger and comes with other signs such as dark urine, belly pain, itching, or unusual tiredness. Many living with Gilbert syndrome who also have conditions that break down red blood cells faster, such as some anemias, may have higher bilirubin levels and more noticeable episodes of jaundice. There is also some evidence that people with Gilbert syndrome may be slightly more prone to pigment gallstones, though many never develop them. If early symptoms of Gilbert syndrome seem to change, last longer than usual, or come with new symptoms, it is worth checking with a doctor so another condition is not missed.
How genes can cause diseases
Humans have more than 20,000 genes, each carrying out one or a few specific functions in the body. One gene instructs the body to digest lactose from milk, another tells the body how to build strong bones and another prevents the body's cells from beginning to multiply uncontrollably and developing into cancer. As all of these genes combined are the building instructions for our body, a defect in one of these genes can have severe health consequences.
Through decades of genetic research, we know the genetic code of any healthy/functional human gene. We have also identified that in certain positions on a gene, some individuals may have a different genetic letter from the one you have. We call these hotspots "Genetic Variations" or "Variants" in short. In many cases, studies have been able to show that having the genetic letter "G" in the position makes you healthy, but having the letter "A" in the same position disrupts the gene function and causes a disease. Genopedia allows you to view these variants in genes and summarizes all that we know from scientific research, which genetic letters (Genotype) have good or bad consequences on your health or on your traits.
What other conditions can cause similar symptoms to Gilbert syndrome?
Mild yellowing of the skin or eyes can also happen with other liver and gallbladder problems, such as hepatitis, fatty liver disease, or gallstones that block the normal flow of bile. Some blood conditions that break down red blood cells too quickly, called hemolytic anemia, can cause similar yellowing too. If the yellowing comes with belly pain, fever, very dark urine, pale stools, or feeling very unwell, doctors usually look for these other causes rather than Gilbert syndrome.
History
Long before there was a name for Gilbert syndrome, doctors noticed that some otherwise healthy people would occasionally look a little yellow, especially during stress, illness, fasting, or after not getting enough sleep. For many, this was not a daily problem but something that came and went, which made it easy to overlook or mistake for a liver disease.
In recent decades, awareness has grown, but the story began much earlier. In the late 1800s and early 1900s, French doctors carefully described people with mild recurring jaundice who did not seem to have the serious liver damage seen in other conditions. At first, these cases were grouped by symptoms alone. Over time, it became clearer that Gilbert syndrome was a distinct, usually harmless pattern rather than a dangerous illness.
As lab testing improved through the 20th century, doctors were able to measure bilirubin, the yellow pigment that builds up in the blood in Gilbert syndrome. This helped explain why some people had normal liver test results overall yet still developed mild jaundice from time to time. What once seemed puzzling gradually became easier to recognize, especially when symptoms flared during common triggers like dehydration, infection, heavy exercise, or skipping meals.
Later research showed that Gilbert syndrome is linked to the way the body processes bilirubin, and researchers eventually identified a genetic cause. That changed how the condition was understood: not as liver failure, but as a common inherited difference in bilirubin handling. Knowing this history helps explain why Gilbert syndrome is usually found during routine blood work or when someone asks about brief yellowing of the eyes, rather than because it causes ongoing liver damage.