G6PD Deficiency: Symptoms, Causes, Diagnosis, Treatment & Prevention

Introduction

Some inherited conditions can remain unnoticed for years, even when they have been present since birth. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is among the most common inherited enzyme disorders worldwide. Many people discover it only after certain medicines, foods, or infections trigger symptoms^1,2. 

Most people with G6PD deficiency live healthy, normal lives, but recognising triggers is important for preventing complications. This blog covers the symptoms, causes, diagnosis, treatment, and practical tips for understanding and managing G6PD deficiency. 

What Is G6PD Deficiency?

G6PD deficiency is an inherited genetic condition in which the body does not produce enough of the G6PD enzyme, or the enzyme has reduced activity¹. When people with G6PD deficiency are exposed to certain triggers (such as specific medicines, infections, or foods like fava beans), their red blood cells (RBCs) can break down faster than the body can replace them. This process (called haemolysis) can lead to haemolytic anaemia (a condition in which the body does not have enough healthy RBCs to carry oxygen effectively)¹.

Why Is G6PD Important?

G6PD helps the body produce a molecule called NADPH (nicotinamide adenine dinucleotide phosphate) through the pentose phosphate pathway. NADPH keeps glutathione, the main antioxidant in RBCs, in its active form. This antioxidant protects RBCs from oxidative stress damage and prevents them from breaking down too early^1,6. 

Unlike most other cells, mature RBCs cannot make new proteins or generate additional G6PD because they lack a nucleus and other cell structures. As a result, they rely entirely on the G6PD enzyme already present to defend against oxidative stress⁷.  When G6PD activity is too low, exposure to substances that cause oxidative stress, such as certain medications, infections, chemicals, or foods, can damage RBCs and cause them to break down prematurely (haemolysis). This may lead to haemolytic anaemia, reducing the blood’s ability to carry oxygen throughout the body¹.

Causes of G6PD Deficiency

G6PD deficiency is caused by inherited changes (mutations) in the G6PD gene, which provides instructions for making the G6PD enzyme. G6PD deficiency is caused by mutations in the G6PD gene, resulting in reduced or absent G6PD enzyme activity¹.

This mutation is triggered by certain factors such as: 

• Medicines, infections, fava beans, and certain chemicals do not cause G6PD deficiency. Instead, they can trigger symptoms or episodes of haemolysis in people who are already born with the condition¹.

Note: More than 400 genetic variants of G6PD deficiency have been identified. These variants differ in the amount of enzyme activity they produce, which is why some individuals never develop symptoms, while others experience severe episodes of haemolysis⁸. 

Symptoms of G6PD Deficiency

Most people with G6PD deficiency do not have symptoms unless they are exposed to a trigger. When RBCs undergo haemolysis, symptoms can develop suddenly and range from mild to severe. Common G6PD deficiency symptoms include^1,9: 

• Pale skin (pallor) 
• Jaundice (yellowing of the skin and eyes) 
• Dark-coloured urine 
• Fatigue or unusual tiredness 
• Shortness of breath 
• Rapid heartbeat (tachycardia) 
• Abdominal or back pain 
• Fever (particularly if there is an infection) 

Some babies with G6PD deficiency may develop symptoms shortly after birth, including¹: 

• Severe neonatal jaundice that appears within the first few days of life 
• Poor feeding or difficulty feeding 
• Increased or reduced muscle tone 
• Excessive lethargy 
• Seizures 

Rarely, untreated severe jaundice in babies can lead to kernicterus, characterised by permanent brain damage¹.

How Is G6PD Deficiency Diagnosed?

Diagnosis typically involves blood tests that measure G6PD enzyme activity. Based on your symptoms, the doctor may rely on^1,10: 

• Medical history and physical examination to assess symptoms, family history, recent infections, medications, and exposure to triggers such as fava beans. 
• Blood tests, including a complete blood count, bilirubin levels, reticulocyte count, and other tests to detect RBC haemolysis. 
• A G6PD test measures how well the G6PD enzyme in RBCs is functioning. 
• Genetic testing may be recommended in selected cases to identify the specific G6PD gene variant. 

Note: G6PD test results may appear normal during or soon after a haemolytic episode because the tested sample could contain more of younger RBCs with higher G6PD activity and a lower proportion of older RBCs with low G6PD levels¹¹. If G6PD deficiency is still suspected despite a normal test result, your doctor may recommend repeating the test after recovery, usually about 3 months later, for a more accurate diagnosis. 

Important: Babies with unexplained or severe jaundice may be tested for G6PD deficiency, especially if they have a family history or belong to a high-risk population^1,9.

Treatment of G6PD Deficiency

There is no cure for G6PD deficiency. Management mainly focuses on avoiding triggers and treating haemolysis if it occurs. Management options for G6PD deficiency include^1,12. 

• Avoiding the Trigger: The first step is to stop or avoid the medicine, food (such as fava beans), or chemical that triggered the haemolytic episode. 
• Managing Underlying Infections: Since infections can cause more oxidative stress, they should be treated promptly. 
• Seeking Timely Blood Transfusion: People with severe anaemia, based on symptoms and haemoglobin level, may require a blood transfusion to replace damaged RBCs. 
• Phototherapy (for Newborns): Babies with jaundice may need phototherapy thathow to detect g6pd deficiency uses specialised blue light to break down excess bilirubin in the baby’s skin into harmless, water-soluble byproducts. Severe cases may require an exchange transfusion to avoid complications. 
• Supportive Care: Mild cases usually improve after removing the triggering factor, maintaining adequate hydration, and close monitoring. 
• Regular follow-up and education: People with G6PD deficiency should identify which triggers to avoid and should inform doctors of their condition before starting any new medication. 

Possible Complications of G6PD Deficiency

Most people with G6PD deficiency remain healthy if they avoid known triggers. However, repeated or severe episodes of RBC breakdown can lead to complications, including^1,4,9:

• Acute Haemolytic Anaemia: The most common complication, caused by rapid destruction of RBCs after exposure to a trigger. 
• Severe Jaundice in Newborns: High bilirubin levels can occur in affected newborns. If left unaddressed, severe jaundice may lead to kernicterus, a rare but serious type of brain damage. 
• Favism: A severe form of acute haemolytic anaemia that develops after eating fava (broad) beans. Although favism can affect people of any age, it is more common in children, particularly boys, living in areas where G6PD deficiency is more prevalent. 
• Haemoglobinuria: In severe cases, RBC breakdown may release haemoglobin into the urine, causing it to appear dark or reddish-brown. However, not all haemolytic episodes in G6PD deficiency result in haemoglobinuria. 
• Acute Kidney Injury: In rare cases, severe haemolysis can damage the kidneys and require hospitalisation. 
• Chronic Nonspherocytic Haemolytic Anaemia: A small number of people with severe G6PD variants may have ongoing destruction of RBCs, even without obvious triggers. 

Prevention of Haemolytic Episodes in G6PD Deficiency

G6PD deficiency itself cannot be prevented because it is an inherited genetic condition. However, episodes of haemolysis can often be prevented by avoiding known triggers⁹:

• Avoid trigger medications that can cause RBC breakdown. Always inform your doctor or pharmacist that you have G6PD deficiency before starting any new medicine. 
• Avoid fava (broad) beans and other foods known to trigger haemolysis. 
• Address infections promptly, as infections are a common trigger for haemolytic episodes. 
• Stay up to date with recommended vaccinations to help reduce the risk of infections. 
• Be cautious with herbal and alternative medicines, as some may increase the risk of haemolysis. 
• Avoid exposure to naphthalene (mothballs) and other oxidising chemicals. 
• Know the warning signs of haemolysis, such as jaundice, dark urine, fatigue, and shortness of breath, and seek medical care promptly if they occur. 

Also Read: High Creatinine: Symptoms, Causes, Diagnosis & Treatment

When Should You Consult a Doctor?

Seek medical attention immediately if you (or your child) have G6PD deficiency and develop signs of haemolysis, especially after exposure to a known trigger. You should see a doctor if you experience⁹: 

• Yellowing of the skin or eyes (jaundice) 
• Dark-coloured urine 
• Pale skin 
• Extreme tiredness, weakness, or lethargy 
• Fever, particularly if accompanied by other symptoms 
• Shortness of breath or rapid heartbeat 
• Dizziness or fainting 

Note: For newborns, seek urgent medical care if your baby develops jaundice within the first 24 hours of life, has difficulty feeding, or appears unusually sleepy. Jaundice that develops after the first 24 hours should also be evaluated by a healthcare provider, as early diagnosis and treatment can help prevent complications^1,9,13. 

Conclusion

G6PD deficiency is a common inherited condition that often remains unnoticed until exposure to certain triggers causes RBC breakdown. Although there is no cure, most people with G6PD deficiency can lead healthy, normal lives by recognising triggers, avoiding high-risk medications and foods, and seeking timely medical care when symptoms occur. 

Frequently Asked Questions (FAQs)

References

1. Mak GK, Shah M. Glucose-6-Phosphate Dehydrogenase Deficiency. In: StatPearls. StatPearls Publishing; 2026. Accessed July 15, 2026. http://www.ncbi.nlm.nih.gov/books/NBK470315/ 

2. Bubp J, Jen M, Matuszewski K. Caring for Glucose-6-Phosphate Dehydrogenase (G6PD)–Deficient Patients: Implications for Pharmacy. Pharm Ther. 2015;40(9):572-574. Accessed July 15, 2026. https://pmc.ncbi.nlm.nih.gov/articles/PMC4571844/ 

3. Cappellini MD, Fiorelli G. Glucose-6-phosphate dehydrogenase deficiency. Lancet. 2008;371(9606):64-74. doi:10.1016/S0140-6736(08)60073-2 https://medlineplus.gov/genetics/condition/glucose-6-phosphate-dehydrogenase-deficiency/

4. Koromina M, Pandi MT, van der Spek PJ, Patrinos GP, Lauschke VM. The ethnogeographic variability of genetic factors underlying G6PD deficiency. Pharmacol Res. 2021;173:105904. doi:10.1016/j.phrs.2021.105904 https://pubmed.ncbi.nlm.nih.gov/34551338/

5. Awab GR, Aaram F, Jamornthanyawat N, et al. Protective effect of Mediterranean-type glucose-6-phosphate dehydrogenase deficiency against Plasmodium vivax malaria. eLife. 10:e62448. doi:10.7554/eLife.62448 https://pubmed.ncbi.nlm.nih.gov/33543710/

6. Stanton RC. Glucose-6-Phosphate Dehydrogenase, NADPH, and Cell Survival. Iubmb Life. 2012;64(5):362-369. doi:10.1002/iub.1017 https://pubmed.ncbi.nlm.nih.gov/22431005/

7. Karafin MS, Francis RO. Impact of G6PD status on red cell storage and transfusion outcomes. Blood Transfus. 2019;17(4):289-295. doi:10.2450/2019.0092-19  https://pmc.ncbi.nlm.nih.gov/articles/PMC6683872/

8. McDonagh EM, Thorn CF, Bautista JM, Youngster I, Altman RB, Klein TE. PharmGKB summary: very important pharmacogene information for G6PD. Pharmacogenet Genomics. 2012;22(3):219-228. doi:10.1097/FPC.0b013e32834eb313 https://pmc.ncbi.nlm.nih.gov/articles/PMC6683872/

9. Favism. Healthdirect. February 5, 2026. Accessed July 15, 2026. https://www.healthdirect.gov.au/G6PD-deficiency 

10. G6PD Test. MedlinePlus Medical Test. Accessed July 15, 2026. https://medlineplus.gov/lab-tests/g6pd-test/ 

11. Arese P, Gallo V, Pantaleo A, Turrini F. Life and Death of Glucose-6-Phosphate Dehydrogenase (G6PD) Deficient Erythrocytes – Role of Redox Stress and Band 3 Modifications. Transfus Med Hemotherapy. 2012;39(5):328-334. doi:10.1159/000343123 https://pmc.ncbi.nlm.nih.gov/articles/PMC3678266/

12. Garcia AA, Koperniku A, Ferreira JCB, Mochly-Rosen D. Treatment Strategies for Glucose-6-Phosphate Dehydrogenase Deficiency: Past and Future Perspectives. Trends Pharmacol Sci. 2021;42(10):829-844. doi:10.1016/j.tips.2021.07.002 https://pubmed.ncbi.nlm.nih.gov/34389161/

13. Ansong-Assoku B, Adnan M, Daley SF, Ankola PA. Neonatal Jaundice. In: StatPearls. StatPearls Publishing; 2026. Accessed July 20, 2026. http://www.ncbi.nlm.nih.gov/books/NBK532930/ 

14. Israel A, Schäffer AA, Berkovitch M, et al. Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency and Long-Term Risk of Immune-Related diseases. medRxiv. Published online March 24, 2023:2023.03.23.23287616. doi:10.1101/2023.03.23.23287616 https://pubmed.ncbi.nlm.nih.gov/37753082/

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