Skip to main content

Glucose-6-Phosphate Dehydrogenase (G6PD)

G6PD is an enzyme that helps protect red blood cells from being destroyed after they are exposed to certain "triggers" (certain medicines and some foods). When red blood cells are destroyed, the low blood cell counts cause a temporary condition known as "anemia" . Some people do not have enough G6PD to protect their red blood cells . This condition is known as G6PD deficiency. G6PD deficiency is caused by inherited variations in the G6PD gene. Because this is a genetic condition, G6PD deficiency is a life-long condition.

More than one hundred such variations (changes) can exist in the G6PD gene. These changes can lead the body to produce  a G6PD enzyme with little or no function. There is a system  to classify people into three categories based on how well their G6PD prevents red blood cell  damage. Clinicians use that system to help guide drug therapy decisions.

G6PD deficiency

People with G6PD deficiency have little or no working G6PD enzyme. About 400 million people have deficient G6PD enzyme activity. This deficiency is more common in people of African, Mediterranean or Southeast Asian descent. About 2 percent of people fall into this group. Without enough G6PD, certain medicines and foods can cause red blood cells to break down and lose their ability to carry oxygen. This condition is known as "hemolytic anemia"

Medicines that should to be avoided in people with G6PD deficiency include:
  • Dapsone
  • Methylene Blue (ProvayBlue®)
  • Pegloticase (Krystexxa®)
  • Toluidine blue
  • Primaquine at standard doses
  • Rasburicase (Elitek®)
  • Tafenoquine (Arakoda®, Krintafel®)
Medicines that should be used with caution in patients with G6PD deficiency include:
  • Nitrofurantoin
  • Primaquine at medium doses
Certain foods and chemicals should also be avoided. These include fava beans and products such as naphthalene (found in moth balls). To learn more about medicines that should be used with caution if you are G6PD deficient, talk to your doctor or pharmacist.

Variable G6PD enzyme activity

Patients in this group may have G6PD activity ranging from normal to deficient. A G6PD enzyme activity test can be used to find out the G6PD activity of patients in this group. About 2 percent of people fall into this group.  

Normal G6PD enzyme activity

Most medicines don't need to be adjusted for this group:

About 96 percent of people have normal G6PD enzyme function. No medicines or foods should be avoided based on G6PD status alone.

More information for patients

More information for healthcare professionals

Legal Disclaimer: This page is intended to provide implementers with guidance on establishing a clinical pharmacogenetic program at their institution. Information contained on this page is for information and educational purposes only. Although reasonable efforts have been made to ensure that the information provided on this page is current, complete and, where appropriate, based on scientific evidence, St. Jude Children's Research Hospital makes no assurances as to whether the provided information will at all times be current or complete. St. Jude Children's Research Hospital, in offering this document, is not providing medical advice or offering a consultative opinion, and is not establishing a treatment relationship with any given individual. You, therefore, should not substitute information contained herein for your own professional judgment, nor should you rely on information provided herein in rendering a diagnosis or choosing a course of treatment for a particular individual.