OVERVIEW

What is favism?

Favism, also known as "broad bean jaundice," is a disease characterized by acute hemolysis after consuming fava beans, fava bean products, or exposure to fava bean pollen. Clinical manifestations mainly include fever, yellowing of the skin and whites of the eyes (jaundice), anemia, dark brown urine (hemoglobinuria), and may be accompanied by dizziness, nausea, vomiting, and abdominal pain.

Favism is a type of glucose-6-phosphate dehydrogenase (G6PD) deficiency. Due to the lack of G6PD in the patient's body, red blood cells are prone to spontaneous rupture and hemolysis. Individuals with favism are more likely to experience hemolysis after consuming fava beans.

Is favism more common in southern Chinese?

Yes. In China, this disease is mainly found in the Yangtze River basin and provinces to the south, with higher incidence rates in Yunnan, Hainan, Guangdong, Guangxi, Fujian, Sichuan, Jiangxi, and Guizhou. Northern regions have relatively lower incidence rates.

Are favism and G6PD deficiency the same thing?

Strictly speaking, no. G6PD deficiency is a broad category of diseases, and favism is one type within it. G6PD-deficient patients do not only develop symptoms after consuming fava beans; they may also experience hemolysis triggered by certain medications, chemicals, infections, or other factors. In severe cases, hemolysis may even occur without any obvious trigger.

SYMPTOMS

What are the clinical manifestations of hemolytic anemia caused by favism?

• Acute onset: Symptoms typically appear within 2 hours to 15 days (mostly 1–2 days) after exposure to fava beans or related products.

• Early warning signs: General discomfort, dizziness, fatigue, weakness, poor appetite, nausea, vomiting, abdominal pain, fever, lasting 1–2 days.

• Disease progression: Rapid onset of pale or yellowish complexion, jaundice, dark or cola-colored urine; some cases may involve hepatosplenomegaly.

• Severe cases: Systemic failure, including severe anemia, lethargy, shock, convulsions, coma, and acute kidney failure.

What are the common types of favism?

The Chinese Academy of Medical Sciences classifies favism into three types: severe, moderate, and mild.

Severe: Patients may develop extreme anemia, significant red blood cells in urine, or severe complications such as pneumonia, heart failure, hepatitis, mental abnormalities, hemiplegia, or strabismus.

Moderate: Intermediate between severe and mild.

Mild: Mild anemia with little or no red blood cells in urine.

CAUSES

Why do patients with favism develop hemolytic anemia?

Patients have a mutation in the glucose-6-phosphate dehydrogenase (G-6-PD) gene, leading to reduced enzyme activity. As a result, red blood cells cannot resist oxidative damage and are destroyed, causing hemolytic anemia.

Hemolytic anemia refers to the rupture of red blood cells, during which hemoglobin inside the ruptured cells transforms into bilirubin.

On one hand, when excessive red blood cells are destroyed, bilirubin levels in the blood rise significantly, causing yellowing of the skin and whites of the eyes (jaundice).

On the other hand, the decrease in hemoglobin responsible for oxygen transport leads to anemia.

In severe cases of hemolysis, undegraded hemoglobin may block renal blood vessels, impairing kidney function and resulting in dark brown urine.

What are the common causes of favism?

Favism occurs shortly after consuming fava beans or inhaling their pollen. The peak season for fava bean ripening is from March to May, during which more cases are reported due to ingestion of fava beans or related products.

There are also reports of breastfed infants developing favism after their mothers consumed fava beans.

Additionally, current evidence suggests that eating bitter melon may also pose a risk of triggering favism.

Is favism hereditary?

Favism is a genetic disorder. The disease-causing gene follows an X-linked incomplete dominant inheritance pattern.

Male hemizygotes and female homozygotes both exhibit significant G6PD deficiency. Female heterozygotes (carrying the mutation on one X chromosome) may or may not develop symptoms depending on the proportion of G6PD-deficient cells in their cell population, resulting in varying clinical manifestations—hence termed incomplete dominance.

Who is most commonly affected by favism?

It predominantly occurs in children aged 1–7 years, with males being far more susceptible than females, at a ratio of approximately 7:1.

Will a child with favism still develop symptoms as an adult?

The condition is incurable. Even after growing up, individuals with favism will still experience symptoms if they consume fava beans or are exposed to their pollen. Lifelong preventive measures are necessary.

DIAGNOSIS

What are the diagnostic criteria for favism?

• History of consuming fava beans within the past two weeks;

• Presence of typical clinical manifestations, such as pale or sallow complexion, jaundice, dark or cola-colored urine, hepatosplenomegaly, etc.;

• Laboratory test results confirming G6PD deficiency.

What laboratory tests can confirm favism?

Methemoglobin reduction test, fluorescent spot test, nitroblue tetrazolium (NBT) paper test, and quantitative G6PD assay. All four tests can confirm G6PD deficiency.

TREATMENT

How to treat hemolytic anemia caused by favism?

• Remove triggering factors: Stop consuming fava beans and their products. In severe cases, induce vomiting, gastric lavage, and laxatives may be used;

• Symptomatic treatment: Intravenous fluids to replenish blood volume, etc.;

• Blood transfusion: Mild anemia may resolve on its own after removing the triggering factors, and transfusion is not required. For severe anemia, 1-2 transfusions of normal red blood cells may be administered;

• Hormone therapy: Hormones have no special efficacy in stopping disease progression, but for critical cases such as high fever, severe headache, coma, or shock, dexamethasone or hydrocortisone may be used to alleviate symptoms. However, this should not replace treatments like blood transfusion or fluid replacement;

• For renal failure, treatments such as hemodialysis may be required.

What precautions should be taken when transfusing blood for favism patients?

Severe cases may require blood transfusion, which is the most important and effective measure during treatment. Precautions for blood transfusion include:

• Do not transfuse blood donated by relatives;

• Donors must be asked about any similar personal or family history. If present, their blood should not be used;

• Do not transfuse blood from donors who have recently consumed fava beans or related products;

• Some patients may develop a low-grade fever after transfusion, which is a mild immune reaction (slight rejection of foreign blood components). Short-term low-grade fever does not require treatment, but temperature fluctuations should be closely monitored. For high fever, physical measures like warm water sponging or ice packs/caps can be used to reduce fever, or antipyretic drugs may be administered.

Can favism be cured?

There is currently no definitive cure. Since most favism patients are generally as healthy as normal individuals when not experiencing an episode, and only develop symptoms under certain triggers—especially consuming fava beans—the most important measure is to prevent exposure to these triggers.

DIET & LIFESTYLE

What are the precautions for observing and handling urine in favism patients?

Monitor changes in the patient's urine volume and color, conduct daily urine routine tests and measure urine pH levels. Provide symptomatic treatment based on test results to prevent kidney damage.

If urine color continues or progressively darkens, and daily urine volume is less than 90–350 mL, it indicates disease progression or kidney damage. In such cases, fluids should be administered to maintain effective circulation and ensure blood supply to vital organs.

If there is no residual urine in the bladder and urine output is low, a small dose of diuretics may be used appropriately. If urine is present in the bladder but output is low, apply warm compresses to the lower abdomen, listen to running water sounds, or gently massage to facilitate urination.

What are the daily precautions for favism patients?

• Avoid consuming fava beans and their products, and avoid exposure to fava bean pollen.

• Do not use naphthalene mothballs in wardrobes for pest control.

• Avoid using gentian violet.

• Do not take medications without medical advice. Inform healthcare providers of this condition, and ensure all medications are prescribed by a doctor. Avoid or use caution with drugs that may trigger favism to prevent recurrence.

• Seek immediate medical attention if symptoms such as yellow skin, anemia, or dark red, tea-colored, or soy-sauce-colored urine appear.

What medications should favism patients avoid or use with caution?

Prohibited drugs: Acetanilide, methylene blue, nitrofurantoin, furazolidone, nitrofurazone, phenylhydrazine, primaquine, plasmoquine, pamaquine, sulfonamides, sulfacetamide, sulfapyridine, thiazolidone, toluidine blue, sulfamethoxazole, etc.

Drugs to use with caution: Phenacetin, aspirin, aminopyrine, antipyrine, trihexyphenidyl, vitamin C, vitamin K, chloramphenicol, streptomycin, isoniazid, sulfadiazine, sulfaguanidine, sulfisoxazole, chloroquine, colchicine, diphenhydramine, levodopa, phenytoin sodium, procainamide, pyrimethamine, quinidine, quinine, etc.

Patients should never self-medicate and must inform healthcare providers of their condition. All medications should be taken under medical supervision.

Can favism patients have children?

Yes, but the likelihood of passing favism to offspring is high.

Newborns can be tested for G6PD deficiency. If diagnosed, preventive measures should be taken: lifelong avoidance of fava beans, staying away from fava bean pollen during the ripening season (March–May), avoiding clothes stored with mothballs, and strictly avoiding triggering drugs (see above). With proper precautions, the disease may never manifest.

Can favism babies receive routine immunization vaccines?

Yes, but close monitoring is required after vaccination.

Can favism babies drink formula milk?

Yes.

Favism patients should use vitamin K₁ and vitamin C with caution. Some formulas contain these ingredients, but the amounts are minimal, and no cases of formula triggering favism have been reported.

Do favism patients need to avoid all beans?

There is no evidence that beans other than fava beans can trigger favism. Patients can consume other legumes.

Can favism patients buy cold medicine from a nearby pharmacy?

No.

Some medications, especially compound or herbal fever/pain relievers or anti-inflammatory drugs, may not clearly state their ingredients and could trigger the disease. Additionally, many new drugs worldwide have not been clinically tested for favism and are not listed as prohibited. Always consult a doctor before use.

Is prenatal diagnosis necessary for favism?

Favism is not a mandatory prenatal screening item. Some patients show no symptoms without triggers, but severe clinical manifestations may occur if the disease is activated. A doctor should assess the need based on individual cases.

What should favism patients consider when taking medications?

Although lists of prohibited and cautionary drugs exist, they may not cover all medications. Besides following a doctor's advice, patients can refer to these G6PD deficiency websites for comprehensive drug-related information:
www.g6pd.org
www.g6pddeficiency.org

PREVENTION

What are the preventive measures for hemolytic anemia in favism?

• If there is a family history of favism, blood relatives should avoid consuming fava beans and their products, and avoid exposure to fava bean pollen;

• If either spouse has a family history of favism, the woman should avoid eating fava beans and their products during pregnancy and breastfeeding;

• In areas with adequate resources, G6PD deficiency screening should be conducted, especially during the neonatal period.

What are the preventive measures for hemolytic anemia in children with favism?

• Conduct prenatal G6PD testing for expectant parents (those already tested before marriage may skip this);

• Advise pregnant women to avoid hemolysis-inducing drugs and abstain from consuming fava beans;

• Collect umbilical cord blood after birth to test for G6PD deficiency;

• Monitor serum total bilirubin levels. If the daily increase is too rapid or the value is too high, administer phototherapy and, if necessary, provide blood transfusion or even exchange transfusion.