What side effects can G6PD deficiency cause?

G6PD helps protect red blood cells from chemical stress. With a deficiency, an infection, particular medicines, or other triggers can damage these cells faster than the body replaces them. The resulting haemolysis can cause anaemia and release pigment that darkens urine. Yellow skin or eyes may occur when bilirubin rises. Symptoms can begin quickly, and a person may feel well between episodes.

The effects vary with the trigger and the person’s enzyme activity. A symptom does not identify the cause by itself, so assessment and testing are needed.

Tell every healthcare professional and pharmacist that you have G6PD deficiency. Check new medicines with a clinician, avoid known personal triggers, and seek advice early during a significant infection. Do not self-treat with leftover medicines. A blood test may help assess anaemia and support diagnosis; see [Blood Test](/treatments/diagnostics-and-screening/blood-test/).

Get urgent care for severe weakness, dizziness or fainting, difficulty breathing, chest discomfort, yellowing that is rapidly worsening, or very dark urine. These signs can accompany substantial haemolysis. See [Dark Urine](/symptoms/dark-urine/) and [Pale Skin](/symptoms/pale-skin/) for symptom context.

Ask which medicines and exposures are unsafe, how to manage infections, and which symptoms require emergency help. Ask whether your family members need information or testing.