Health condition
G6PD deficiency
G6PD deficiency is the world's most common enzyme deficiency: red cells are vulnerable to oxidative stress, so certain drugs, fava beans and infections can trigger sudden haemolysis - avoidance keeps most people entirely well.
Why trust this guide
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Editorial team
Written by our editorial team from the UK sources listed on each page.
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Sourced from guidance
Checked against current NHS and UK specialist society guidance at the time of review.
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Current for 2026
Reviewed on 2026-09-27 with the next review scheduled for 2027-09-27.
Key facts
The essentials at a glance.
Which gene and test confirm it, who should be tested in the family, and which specialist to see.
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Caused by G6PD gene variants; X-linked, so predominantly affects men, though female carriers can be symptomatic
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Triggers: drugs such as dapsone, primaquine, rasburicase, nitrofurantoin and some sulfonamides; fava (broad) beans; infections; naphthalene
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A haemolytic episode: sudden fatigue, jaundice, dark urine and dropping haemoglobin one to three days after exposure
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Diagnosis: G6PD enzyme assay - best checked away from an acute episode, when reticulocytes can mask deficiency
Understanding the condition
What it is and what happens next.
What causes it, how it is confirmed, and the testing and specialist routes available in the UK.
What it is and how it presents
Hundreds of millions of people carry G6PD variants, concentrated in families with Mediterranean, African, Middle Eastern and South-East Asian ancestry, because carriers gained malaria protection. Day to day the deficiency is silent; the risk is episodic, when an oxidising drug, infection or a plate of broad beans overwhelms the red cell's defences and haemolysis follows. Severity varies by variant - Mediterranean-type enzymes tend to produce more dramatic episodes than the common African-type.
Testing, surveillance and specialist care
A quantitative enzyme assay establishes the diagnosis, ideally repeated after recovery if first checked during a crisis, and genotyping clarifies carrier status in women, where mixed cell populations can produce misleadingly normal enzyme levels. A haematologist can supply a personalised safe-drug list - the practical core of managing this condition - and advise on family testing. NHS clinical genetics services carry some of the longest waits in the health service, often many months for a first appointment, whereas private genetic testing and a specialist review can typically be arranged within around two weeks.
Seeing a specialist
Who to see, and how quickly you can be seen.
The specialist for this condition is usually a haematologist. Your GP can refer you on the NHS, or you can arrange a private consultation directly.
A quiet reminder
This guide is for information, not medical advice.
Your GP knows your history and can tell you which parts apply to you. If in doubt, see them - and seek urgent care for any emergency symptoms.
Frequently asked
Common questions about G6PD deficiency.
Quick, plain-English answers to what people ask us most.
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What does G6PD deficiency mean?
G6PD deficiency is a condition your doctor may diagnose based on your symptoms, medical history and, where needed, examination or test results. Understanding exactly how it applies to your situation is best done with a clinician who can look at your full picture rather than relying on general information alone.
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What are the risk factors for G6PD deficiency?
G6PD deficiency can arise from several different underlying mechanisms, and in many cases more than one factor contributes. Identifying likely causes usually forms part of the initial specialist work-up.
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What are the symptoms of G6PD deficiency?
Symptoms of G6PD deficiency vary from person to person and can range from mild and easily missed to significant enough to affect daily life. Because overlapping conditions can produce similar symptoms, a clinical assessment is the most reliable way to confirm what's actually going on.
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Can G6PD deficiency cause complications?
Most cases of G6PD deficiency are manageable with appropriate care, though, like many conditions, it can occasionally lead to complications if left unassessed or untreated. Your clinician can give you a realistic sense of the risks based on your specific presentation.
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Is G6PD deficiency hereditary or genetic?
Many forms of G6PD deficiency have a genetic or inherited component, and some are linked to specific gene changes that can run in families. If there's a family history, genetic counselling can help clarify the pattern of inheritance and whether relatives might benefit from testing.
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Is there a cure for G6PD deficiency?
G6PD deficiency can often be managed effectively, and in some cases prevented or reversed, with the right combination of lifestyle changes, medication or other targeted treatment. A specialist will tailor the approach to your circumstances rather than applying a one-size-fits-all plan.
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How is G6PD deficiency treated?
Treatment for G6PD deficiency is usually built around the severity of your symptoms and any underlying cause found on assessment, and may involve lifestyle measures, medication, physiotherapy or, in some cases, a procedure. Your specialist will discuss the pros and cons of each option with you before agreeing a plan.
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What's the outlook for G6PD deficiency?
The outlook for G6PD deficiency varies widely depending on the underlying cause, how early it's diagnosed, and how it responds to treatment. Many people see significant improvement with appropriate care, and your specialist can give you a more personalised timeframe once they've reviewed your case.
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Could G6PD deficiency be confused with another condition?
Because several conditions can share similar symptoms to G6PD deficiency, clinicians often consider a short list of possibilities before confirming a diagnosis. This is one of the main reasons a proper assessment, and sometimes targeted tests, matters more than relying on symptoms alone.
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When should I see a doctor about G6PD deficiency, and how quickly can I be seen privately?
It's worth seeking medical advice if symptoms of G6PD deficiency are persistent, worsening, or affecting your daily life, rather than waiting for them to resolve on their own. NHS routine referrals for this kind of assessment can take anywhere from around 20 to 45+ weeks, whereas private consultants typically offer an appointment within about two weeks.