Dapsone: a common treatment for Sweet’s syndrome

Updated 12/03/17.

Corticosteroids (steroids) such as prednisone are the main form of treatment for Sweet’s syndrome, but sometimes other medications are given. These include colchicine, potassium iodide, ciclosporin, dapsone, and others. Read more about treatment options here.

What is dapsone?

Dapsone is an antibacterial medication (sulphonamide class or sulfa drug) that also has an anti-inflammatory effect. It is used to treat vasculitis and certain types of skin condition.

What are the potential side-effects of dapsone?

Dapsone is usually well tolerated, and even though some people do experience side-effects, not everyone does.

Common side-effects include:

  • Headaches.
  • Nausea.
  • Vomiting.

Other side effects:

  • Changes in the red blood pigment (haemoglobin) that can lead to a bluish discolouration of the lips and fingertips that does not cause other symptoms.
  • 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.

See ‘Important,’ and ‘Further information’ to learn more about the side-effects of dapsone.

Will I need to be monitored before or while taking dapsone?

Yes. Your doctor will need to:

  • Check for G6PD deficiency, and take blood tests to make sure that your blood, liver and kidneys are working normally before starting dapsone.
  • Monitor you while taking dapsone so that any potentially serious side-effects can be detected as early as possible. You will be given regular blood tests, at first frequently, and then reduced to every three months once the dose of dapsone that you are taking has been stabilized.


1. Dapsone may cause low oxygen levels. If this happens, the dapsone will need to be stopped. An urgent blood count needs to be taken if you develop shortness of breath or chest pain.

2. If you develop a skin rash, high temperature, sore throat, mouth ulcers, unexplained bruising or bleeding, contact your doctor immediately! This may indicate a fall in blood count.

3. Patients with a known sulfa allergy must be cautious when taking dapsone as there is an increased risk of allergic reaction. Allergy to dapsone can cause fever, a rash and swelling of glands in the neck, armpits and groins (lymphadenopathy). If this happens, the dapsone needs to be stopped and medical advice sought immediately!

4. Antioxidants such as ascorbic acid (vitamin C) or cimetidine tablets can help reduce the risk of anaemia.

5. Dapsone causes increased sensitivity to sunlight. Use a sun cream that has a sun protection factor (SPF) of at least 15, and avoid the use of sunbeds.

6. Try to avoid certain supplements, e.g. alfalfa, as they may increase sensitivity to sunlight.

7. Alcohol is often safe in moderation, but may increase the risk of dapsone side-effects in some people.

Further information.

British Association of Dermatologists (2016) Dapsone: patient information leaflet (online). Updated Dec 2016, and accessed 12/03/17.

Drugs.com (2017) Dapsone (online). Accessed 12/03/17. Includes information on rare side-effects, and professional information.

Mayo Clinic (2017) Dapsone: oral route (online). Accessed 12/03/17. Includes a list of rare side-effects.

Mayo Clinic (2014) Drug allergy. I have a sulfa allergy. Do I need to avoid certain medications? (online). Accessed 12/03/17.

Oakley, A. (1997) Dapsone. DermNet NZ (online). Accessed 12/03/17. Includes a short list of rare side-effects, and information on both oral and topical (gel) dapsone.

© 2012-2017 Sweet’s Syndrome UK


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