For patients taking dapsone for leprosy:

• To help clear up your leprosy completely or to keep it from coming back, it is very important that you keep taking this medicine for the full time of treatment, even if you begin to feel better after a few weeks or months. You may have to take it every day for as long as 3 years or more, or for life. If you stop taking this medicine too soon, your symptoms may return.
• This medicine works best when there is a constant amount in the blood. To help keep the amount constant, do not miss any doses. Also, it is best to take each dose at the same time every day. If you need help in planning the best time to take your medicine, check with your health care professional.

For patients taking dapsone for dermatitis herpetiformis:

• Your doctor may want you to follow a gluten-free diet. If you have any questions about this, check with your doctor.

Dosing

The dose of dapsone will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of dapsone. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking dapsone.

• For oral dosage form (tablets):
  • For Hansen's disease (leprosy):
    • Adults and teenagers 50 to 100 milligrams (mg) once a day; or 1.4 mg per kilogram (kg) (0.6 mg per pound) of body weight once a day. Dapsone should be taken with other medicines to treat Hansen's disease.
    • Children Dose is based on body weight. The usual dose is 1.4 mg per kg (0.6 mg per pound) of body weight once a day. Dapsone should be taken with other medicines to treat Hansen's disease.
  • For dermatitis herpetiformis:
    • Adults and teenagers 50 mg once a day to start. Your doctor will increase your dose, up to 300 mg once a day, until your symptoms are controlled. Then your dose will be decreased to the lowest dose that will still control your symptoms.
    • Children Dose is based on body weight. The usual dose is 2 mg per kg (0.9 mg per pound) of body weight once a day to start. Your doctor will increase your dose until your symptoms are controlled. Then your dose will be decreased to the lowest dose that will still control your symptoms.

Missed dose

You may skip a missed dose if it does not make your symptoms come back or get worse. If your symptoms do come back or get worse, take the missed dose as soon as possible. Then go back to your regular dosing schedule.

Storage

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For dapsone, the following should be considered:

Allergies Tell your doctor if you have ever had any unusual or allergic reaction to dapsone or sulfonamides. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy Studies have not been done in humans or animals. However, reports on the use of dapsone in humans have not shown that this medicine causes birth defects or other problems.

Breast-feeding Dapsone passes into the breast milk. Dapsone may cause blood problems in nursing babies with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Breast-feeding may need to be stopped because of the risks to the baby.

Children Although there is no specific information comparing use of dapsone in children with use in other age groups, this medicine is not expected to cause different side effects or problems in children than it does in adults.

Older adults Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. There is no specific information comparing use of dapsone in the elderly with use in other age groups.

Other medicines Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking dapsone, it is especially important that your health care professional knows if you are taking any of the following:

• Acetohydroxamic acid (e.g., Lithostat) or
• Antidiabetics, oral (diabetes medicine you take by mouth) or
• Furazolidone (e.g., Furoxone) or
• Methyldopa (e.g., Aldomet) or
• Nitrofurantoin (e.g., Furadantin) or
• Primaquine or
• Procainamide (e.g., Pronestyl) or
• Quinidine (e.g., Quinidex) or
• Quinine (e.g., Quinamm) or
• Sulfonamides (sulfa medicine) or
• Vitamin K (e.g., AquaMEPHYTON, Synkayvite) Use of dapsone with these medicines may increase the chance of side effects affecting the blood

• Dideoxyinosine (e.g., ddI, Videx) Use of dideoxyinosine with dapsone may decrease the effectiveness of dapsone

• Anemia (severe) or
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency or
• Methemoglobin reductase deficiency There is an increased risk of severe blood disorders and a decrease in red blood cell survival

• Liver disease Dapsone may on rare occasion cause liver damage