Dapsone

This leaflet has been written to help you understand more about dapsone. It tells you what it is, how it can be used to treat skin conditions, and where you can find out more about it.

Dapsone is a sulphonamide antibiotic. It is available only on prescription. It acts as an anti-inflammatory drug and has been used successfully to treat several skin conditions such as dermatitis herpetiformis, pyoderma gangrenosum, Sweet’s syndrome, and vasculitis for many years. It can, under the supervision of your dermatologists, also be used for other inflammatory skin conditions that are not mentioned here if none of the standard treatments are useful. 

If you know that you are allergic to dapsone or have had severe reactions to the sulphonamide group of medicines, you must not take dapsone. The dose of dapsone may need to be lower than usual if you have a heart or lung disease, have a condition called G6PD deficiency (see below), or if you are anemic. It is important to tell your doctor about these conditions.

Dapsone is usually well-tolerated but should be started cautiously. Some people experience mild headaches or sickness. Changes in the red blood pigment (hemoglobin) can lead to the lips and fingertips having a bluish appearance. Rarely, it may cause bone marrow suppression (a decrease in the ability of the bone marrow to produce cells), which can cause fever, mouth ulcers, a sore throat, bruising or prolonged bleeding. 

Dapsone may cause anemia, shortness of breath, and tiredness, especially in those with a genetic condition called glucose-6-phosphate dehydrogenase (G6PD) deficiency, which is more common in those with the Mediterranean, African and Asian ancestry. The level of G6PD can be tested for this deficiency before dapsone is prescribed. Your doctor should check whether you have G6PD deficiency before prescribing dapsone. 

Allergy to dapsone can cause fever, a rash, and swelling of glands in the neck, armpits, and groins (lymphadenopathy). Please stop dapsone if you have an allergic reaction and seek advice from your GP or dermatologist.

Rarely, prolonged use of dapsone over months or years at a high dose can lead to impaired function of nerves in the limbs, causing weakness of muscles in the hands and feet. 

Your doctor will advise you on the correct dose to take. Dapsone is available in tablet form at strengths of 50 mg and 100 mg. The usual dose would be in the range of 50 to 200 mg daily. 

It is essential to have a blood test to ensure your blood counts, liver, and kidney functions are normal before starting dapsone. Blood tests will frequently occur after the first starting dapsone and can be reduced to every three months when the dose is stabilized.

An urgent blood count needs to be taken immediately if you develop any symptoms as outlined above. 

Dapsone can reduce the number of sperm and their mobility. It does not affect the development of the growing baby. If dapsone has to be taken in pregnancy, then the mother should take folic acid 5 mg daily. 

Yes, dapsone can be found in breast milk, but the risk to babies is minimal unless they have G6PD deficiency. 

Yes, always in moderation. 

You should avoid probenecid (a treatment for gout), the antibiotics trimethoprim and rifampicin, saquinavir (a treatment for HIV infection), and typhoid vaccine. It is essential that you always tell your doctor and pharmacist you are taking dapsone.