Oral dapsone is a generic drug taken by mouth to treat certain skin conditions such as Hansen’s disease (leprosy) and dermatitis herpetiformis (celiac rash), an extremely itchy skin rash experienced by people with a sensitivity or intolerance to gluten.
Topical dapsone (Aczone) is a gel applied to the skin to treat acne vulgaris caused by blocked hair follicles.
This article discusses dapsone’s mechanism of action, how it works, its uses, side effects, and precautions.
Dapsone Mechanism of Action
Dapsone, also called 4,4’-sulfonyldianiline (SDA) or diaminodiphenyl sulfone (DDS), is a century-old sulfone drug first synthesized in 1908. Dapsone’s dual function characterizes its mechanism of action as both an antimicrobial (which slows the growth of bacteria) and a nonsteroidal anti-inflammatory (which reduces inflammation without steroids).
Unlike bactericidal antibiotics, which kill bacteria, oral dapsone is a bacteriostatic antibiotic that prevents bacteria from growing and multiplying without killing them. Bacteriostatic antibiotics, like dapsone, disrupt folic acid metabolism, which bacteria need to grow and multiply.
Although dapsone’s ability to reduce inflammation is well-established and has proven clinical benefits, its precise anti-inflammatory mechanism of action remains unclear.
Dapsone Uses
Since the early 20th century, oral dapsone has been used in combination with other drugs to treat leprosy. This U.S. Food and Drug Administration (FDA)-approved sulfone drug is a bacteriostatic agent that slows the growth of Mycobacterium leprae (the bacterium that causes Hansen’s disease) via inhibition (blockage) of the folic acid pathway (needed for cellular growth).
Because oral dapsone is no longer patented, it’s sold as a generic and is relatively inexpensive. Oral dapsone is also FDA-approved to treat the “gluten rash” associated with celiac disease called dermatitis herpetiformis.
Although oral dapsone is only FDA-approved to treat leprosy and dermatitis herpetiformis, it’s used off-label to treat other skin conditions, such as chronic idiopathic (hives lasting six weeks or longer with no known cause) and autoimmune urticaria (hives).
Topical dapsone is sold under the brand name Aczone and is FDA-approved to treat acne vulgaris. Like oral dapsone, topical Aczone gel has both anti-inflammatory and anti-microbial properties.The double effect of reducing inflammation and slowing bacterial growth makes topical dapsone a very effective acne treatment.
Side Effects
Dapsone is well tolerated by most people and has a good safety profile. However, it reduces hemoglobin (protein in blood cells) and has a long history of causing hemolytic anemia (a low amount of healthy red blood cells), especially in people with G6PD deficiency (a common enzyme deficiency). Another severe side effect associated with the long-term administration of dapsone is methemoglobinemia, which occurs when elevated levels of methemoglobin lessen red blood cells’ ability to transport oxygen.
Other less severe side effects associated with oral dapsone include:
Peripheral neuropathy (nerve damage) Gastrointestinal effects (stomach ache) Vertigo (spinning sensation) or dizziness Insomnia Headache
Topical dapsone is much less likely to cause the same severe side effects as oral dapsone. However, Aczone can cause methemoglobinemia and hemolytic anemia. That said, most people don’t experience severe side effects from Aczone.
The most common side effects from Aczone (topical dapsone gel) occur directly on the affected area of the skin that’s being treated. These side effects include:
Stinging/burning skin sensations Skin redness Dry skin patches Peeling skin Itchy skin
Precautions
Anyone taking oral dapsone for extended periods should have frequent complete blood count tests to ensure stable hemoglobin and methemoglobin levels. Liver and kidney functions should also be closely monitored while taking this medication.
Oral and topical dapsone can make your skin more sensitive to sunlight.Avoid prolonged sun exposure while taking this medication.
Summary
Dapsone’s unique mechanism of action is characterized by its anti-bacterial and anti-inflammatory properties. Dapsone is an “old drug” that was first synthesized in 1908, but it’s not outdated. Even though this drug was invented over 100 years ago, its dual ability to slow bacterial growth and reduce inflammation makes this sulfone drug incredibly effective when treating skin disorders such as Hansen’s disease, dermatitis herpetiformis, and acne vulgaris.
A Word From Verywell
Dapsone has the unique ability to reduce inflammation and slow bacterial growth, which is a great combination. This drug is highly effective at treating certain skin disorders but also hard on your red blood cells. If you have to take dapsone for an extended period, closely monitor your blood and liver functions to ensure that your body is safely handling the long-term dosage.
