The essentials

Gilbert syndrome is a common, inherited and harmless condition in which the liver clears bilirubin more slowly than usual. It affects 3 to 7 in 100 Americans and often shows up by chance: a mildly raised indirect bilirubin with normal liver enzymes. It needs no treatment and does not shorten life, but a few medicines need care. See a doctor promptly if yellowing comes with dark urine, pale stools or itching.

What is Gilbert syndrome, at a glance?

Gilbert syndrome, also called Gilbert's syndrome, Gilbert's disease or, in German-speaking countries, Meulengracht disease, is a mild inherited difference in how the liver handles bilirubin[1]. Bilirubin is the yellow pigment made when old red blood cells are broken down. The liver normally attaches a sugar molecule to it (a step called conjugation) so it can leave the body in bile. In Gilbert syndrome, the enzyme that does this works at about 30% of its normal level, so unconjugated bilirubin builds up a little in the blood[1].

  • How common: about 3 to 7% of Americans[1]; worldwide estimates range from about 2 to 13% depending on the population[6].
  • Who: more often diagnosed in males, often around puberty or in young adulthood[2][6].
  • Key blood tests: total and direct bilirubin, liver enzymes and a complete blood count[6].
  • Outlook: it does not damage the liver and does not affect life expectancy[2].

What are the symptoms of Gilbert syndrome?

About 30% of people with Gilbert syndrome have no signs or symptoms at all; they learn about it from a blood test done for another reason[1]. When symptoms appear, they are usually mild and come and go:

  • Common No symptoms, only a slightly high bilirubin on a lab report[1].
  • Possible Short episodes of mild jaundice: a yellow tinge to the whites of the eyes or the skin. On brown or black skin, the whites of the eyes are the easiest place to see it[2].
  • Possible Tiredness or abdominal discomfort during episodes[1].
  • Rare Visible jaundice that is marked or long lasting[1].

Episodes tend to follow a trigger: fasting or skipping meals, dehydration, illness such as a cold or flu, vigorous exercise, poor sleep, alcohol or menstruation[1][2]. Gilbert syndrome does not usually cause itching, dark urine or pale stools; if these appear, another cause is more likely and should be checked[2]. The urine color guide explains what dark urine can mean.

When should I see a doctor?

When to see a doctor

  • Emergency: call 911 for yellow skin or eyes with confusion, extreme drowsiness, vomiting blood, black stools or severe abdominal pain. These signs do not come from Gilbert syndrome and point to a serious liver, bile duct or blood problem.
  • Within 24 to 48 hours if you notice yellowing for the first time and have never been diagnosed, or if your usual jaundice is stronger than normal or does not fade within a few days[2]; also if yellowing comes with dark urine, pale stools, itching, fever or weight loss[2].
  • At your next appointment to discuss a bilirubin flagged H on a routine test, to confirm the diagnosis, and before starting any new long-term medicine[2].

What causes Gilbert syndrome, and is it genetic?

Yes. Gilbert syndrome is inherited and present from birth[1]. It comes from changes in the UGT1A1 gene, which carries the instructions for the liver enzyme that conjugates bilirubin (bilirubin UDP-glucuronosyltransferase)[1].

  • Common In people of European descent, the usual cause is two copies of a small change in the gene's "on switch" (promoter), known as UGT1A1*28. It lowers how much enzyme is made rather than changing the enzyme itself[1][8]. This form is passed on in an autosomal recessive way: both parents pass on a copy[1].
  • Possible In Asian populations, a different change (a missense variant such as UGT1A1*6) is more often involved, and one altered copy can be enough[1][6].
  • Rare When both copies carry more severe changes, the result is a different and much more serious condition, Crigler-Najjar syndrome[1].

Carrying the gene change is necessary but not always sufficient: not everyone with two copies has a raised bilirubin, and levels also depend on sex, diet and other factors[8][6]. You cannot catch Gilbert syndrome, and it cannot be prevented[2].

How is Gilbert syndrome diagnosed, and how do I read the blood test?

In most cases, the diagnosis is made from blood tests alone. The doctor looks for a raised bilirubin that is mostly the unconjugated (indirect) type, on repeated tests, with normal liver enzymes and no sign of hemolysis, which is the breakdown of red blood cells[6][9]. In Gilbert syndrome, bilirubin typically fluctuates between about 1 and 5 mg/dL[6]. Here is a fictitious report with the typical pattern.

Fictitious example of a lab report line (United States format)
TestResultReference rangeFlag
Bilirubin, total2.3 mg/dL0.1-1.2 mg/dLH
Bilirubin, direct (conjugated)0.2 mg/dLLess than 0.3 mg/dL
Bilirubin, indirect (calculated)2.1 mg/dLTotal minus direct
ALT22 U/L4-36 U/L
Hemoglobin15.1 g/dL13.8-17.2 g/dL (male)
  1. Total bilirubin: all the bilirubin in the blood. Here it is above the usual adult range of 0.1 to 1.2 mg/dL, hence the H[3].
  2. Direct bilirubin: the conjugated part, already processed by the liver. It stays normal (under 0.3 mg/dL) in Gilbert syndrome[3][6]. A high direct bilirubin points elsewhere, for example to a bile duct problem.
  3. Indirect bilirubin: often not measured but calculated as total minus direct. Almost all the excess is here, which fits a conjugation problem[6].
  4. ALT and hemoglobin: a normal liver enzyme argues against liver damage, and a normal hemoglobin argues against hemolytic anemia[4][5]. Ranges differ between laboratories; your lab's range is the one that applies.

Bilirubin flagged H but everything else in range? BloodSense reads your whole report, line by line, and shows which results fit together so you can prepare your questions for the doctor.

Get my blood test explained

To rule out other causes, the doctor may also look at the full comprehensive metabolic panel and the complete blood count. If hemolysis is a question, a reticulocyte count, LDH and haptoglobin help: in Gilbert syndrome they are normal[6].

A genetic test for UGT1A1 can confirm the diagnosis but is usually not needed; it is used when the picture is unclear[2][9]. Older "provocation" tests, such as a 24-hour low-calorie fast to see whether bilirubin rises, are rarely used today[6]. For a deeper look at each number, see our guides to total bilirubin results, direct bilirubin and high liver enzymes.

Does Gilbert syndrome need follow-up blood tests?

Once the diagnosis is clear, no regular monitoring is needed for Gilbert syndrome itself, because it does not damage the liver[2]. Your bilirubin will keep moving up and down, often higher after a fast, an illness or a hard workout[1][6]. That is expected.

  • Tell every new care team so that a raised bilirubin on a future test is read correctly.
  • Retest when the pattern changes: a rise in direct bilirubin, abnormal ALT or other liver enzymes, anemia, or new symptoms are not explained by Gilbert syndrome and need their own work-up[6].
  • Combined conditions: Gilbert syndrome together with a blood disorder that shortens red cell life, such as G6PD deficiency, thalassemia or hereditary spherocytosis, can lead to much higher bilirubin and to gallstones; follow-up then depends on the blood disorder[9].

Is there a treatment for Gilbert syndrome, and which medicines need care?

No treatment is needed and there is no cure; the yellowing fades on its own[2]. The main practical point is medicines. The same liver enzyme helps clear several drugs, so some can build up or cause more jaundice[6]. Do not stop a prescribed medicine on your own; tell your doctor and pharmacist about Gilbert syndrome before starting a new one[2].

  • Irinotecan (a chemotherapy drug): people with two reduced-function UGT1A1 copies have a higher risk of severe side effects such as low white blood cells and diarrhea. A Dutch guideline recommends UGT1A1 testing before treatment and a lower starting dose for these patients[11].
  • Atazanavir (an HIV medicine): it blocks the same enzyme and often causes jaundice; the risk of stopping it because of jaundice is highest with two reduced-function copies[10].
  • Statins and some other drugs: some medicines, such as statins for high cholesterol, may need closer monitoring[2]. Acetaminophen, some anti-inflammatory drugs and gemfibrozil also use this pathway[6]: mention the diagnosis rather than avoiding them without advice.

Gilbert syndrome may slightly raise the risk of gallstones, but no other diseases are linked to it[2].

How do I live with Gilbert syndrome, and does diet matter?

Most people live normally. Simple habits can make episodes of yellowing less frequent:

  • Eat regular meals and avoid long fasts or very low-calorie diets[2][12].
  • Drink enough fluids, especially during illness or hot weather[2].
  • Sleep well, avoid overexercising, and keep alcohol low[2].
  • Keep a short diary of episodes to spot your own triggers[2].
  • If you are asked to fast before a blood test, remember that fasting itself can push bilirubin up[6].

There is no special "Gilbert diet". A 2024 systematic review of 19 clinical studies concluded that avoiding excessive calorie restriction, and eating fats, vegetables and fruit, may help prevent jaundice episodes, while noting that more research is needed[12].

There may even be an upside. People with Gilbert syndrome have been found to have lower rates of cardiovascular disease and type 2 diabetes in observational studies, possibly because bilirubin acts as an antioxidant[6][7]. These are associations, not proof.

Questions to ask your doctor

  1. Is my raised bilirubin mostly indirect, with normal direct bilirubin and liver enzymes?
  2. Have hemolysis and other liver problems been ruled out?
  3. Do I need a genetic test, or is the blood pattern enough?
  4. Do any of my current medicines need closer monitoring because of Gilbert syndrome?

Frequently asked questions

Is Gilbert syndrome dangerous?

No. It does not damage the liver, does not usually cause serious health problems and does not affect life expectancy[2]. The main precaution concerns a few medicines.

Can I drink alcohol with Gilbert syndrome?

Alcohol can trigger episodes of yellowing in some people, so it is best kept low[2]. Gilbert syndrome itself does not make the liver more fragile, but heavy drinking harms any liver.

Can Gilbert syndrome cause itchy skin?

It does not usually cause itching. Itching with yellow skin suggests another cause, such as a bile flow problem, and should be checked by a doctor[2].

Can I take ibuprofen or acetaminophen?

Both are partly processed by the same liver pathway[6]. Usual doses are commonly used, but ask your doctor or pharmacist, especially for regular or long-term use[2].

  1. MedlinePlus Genetics. Gilbert syndrome. US National Library of Medicine. medlineplus.gov (accessed November 1, 2026)
  2. NHS. Gilbert's syndrome. National Health Service (UK), reviewed August 4, 2025. nhs.uk (accessed November 1, 2026)
  3. MedlinePlus Medical Encyclopedia. Bilirubin blood test. US National Library of Medicine. medlineplus.gov (accessed November 1, 2026)
  4. MedlinePlus Medical Encyclopedia. ALT blood test. US National Library of Medicine. medlineplus.gov (accessed November 1, 2026)
  5. MedlinePlus Medical Encyclopedia. Hemoglobin. US National Library of Medicine. medlineplus.gov (accessed November 1, 2026)
  6. De Silva AP, Nuwanshika N, Niriella MA, de Silva HJ. Gilbert's syndrome: the good, the bad and the ugly. World J Hepatol. 2025;17(2):98503. doi:10.4254/wjh.v17.i2.98503 (accessed November 1, 2026)
  7. Vítek L, Tiribelli C. Gilbert's syndrome revisited. J Hepatol. 2023;79(4):1049-1055. doi:10.1016/j.jhep.2023.06.004 (accessed November 1, 2026)
  8. Bosma PJ, Chowdhury JR, Bakker C, et al. The genetic basis of the reduced expression of bilirubin UDP-glucuronosyltransferase 1 in Gilbert's syndrome. N Engl J Med. 1995;333(18):1171-1175. doi:10.1056/NEJM199511023331802 (accessed November 1, 2026)
  9. Fretzayas A, Moustaki M, Liapi O, Karpathios T. Gilbert syndrome. Eur J Pediatr. 2012;171(1):11-15. doi:10.1007/s00431-011-1641-0 (accessed November 1, 2026)
  10. Gammal RS, Court MH, Haidar CE, et al. Clinical Pharmacogenetics Implementation Consortium (CPIC) guideline for UGT1A1 and atazanavir prescribing. Clin Pharmacol Ther. 2016;99(4):363-369. doi:10.1002/cpt.269 (accessed November 1, 2026)
  11. Hulshof EC, Deenen MJ, Nijenhuis M, et al. Dutch Pharmacogenetics Working Group (DPWG) guideline for the gene-drug interaction between UGT1A1 and irinotecan. Eur J Hum Genet. 2023;31(9):982-987. doi:10.1038/s41431-022-01243-2 (accessed November 1, 2026)
  12. Goluch Z, Wierzbicka-Rucińska A, Książek E. Nutrition in Gilbert's syndrome: a systematic review of clinical trials according to the PRISMA statement. Nutrients. 2024;16(14):2247. doi:10.3390/nu16142247 (accessed November 1, 2026)

This page is general information. It does not replace the advice of a doctor, who interprets your results with your symptoms, history and examination.