What are the aims of this leaflet?
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.
What is dapsone and what conditions are treated with it?
Dapsone is an antibacterial medicine belonging to the sulphonamide class of antibiotics. It is available only on prescription. It acts as an anti-inflammatory drug and has been used successfully as a treatment for several skin conditions such as dermatitis herpetiformis, pyoderma gangrenosum, Sweet’s syndrome and vasculitis for many years. Sometimes it can be used for other inflammatory skin conditions that are not mentioned here if none of the usual treatments are effective.
When should you not use dapsone?
If you know that you are allergic to dapsone, or have had serious reactions to the sulphonamide group of medicines, you should not take dapsone. Let your doctor know if you have a heart or lung disease, or if you are known to have a condition called G6PD deficiency (see below), or if you are anaemic because the dose of dapsone may then have to be lower than usual.
What are the potential side effects of dapsone?
Dapsone is usually well tolerated but should be started cautiously. Some people experience mild headaches or sickness. Changes in the red blood pigment (haemoglobin) can lead to a bluish discolouration of the lips and fingertips that does not cause other symptoms. Rarely, a fall in the blood count can cause fever, mouth ulcers, a sore throat or bruising.
Dapsone may cause anaemia, shortness of breath and tiredness. This is much more likely if you have a genetic condition called glucose-6-phosphate dehydrogenase (G6PD) deficiency. People of Mediterranean, African and Asian ancestry are especially at risk and 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). Dapsone should be stopped if allergy is suspected and medical advice sought.
Are there any other side effects if dapsone is taken for a long time?
Rarely, prolonged use over months or years at high doses can lead to impaired function of nerves in the limbs, causing weakness of muscles in the hands and feet.
What dose should I take?
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.
How will I be monitored for the side effects of dapsone treatment?
You will need blood tests to make sure that your blood, liver and kidneys are working normally before starting dapsone. These tests will take place frequently after first starting dapsone and can be reduced to every three months when the dose is stabilised and you remain on the dapsone. An urgent blood count needs to be taken immediately if you develop any symptoms such as shortness of breath or chest pain.
Does dapsone affect fertility or pregnancy?
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.
Does dapsone affect breast feeding?
Yes but only if the baby suffers from G6PD deficiency. There have not been any reported concerns in other babies.
May I drink alcohol while taking dapsone?
What other medicines I should avoid when taking dapsone?
You should avoid probenecid (a treatment for gout), and the antibiotics trimethoprim and rifamycins, saquinavir (a treatment for HIV infection) and typhoid vaccine.
It is important that you always tell your doctor and pharmacist that you are taking dapsone.
Where can I find out more about dapsone?
This information sheet does not list all the side effects this type of drug can cause. For fuller details, please look at the drug information leaflet that comes with your medicine.