This medication is used to treat a certain type of skin disorder (dermatitis herpetiformis). It is also used with other drugs to treat Hansen's disease. Dapsone belongs to a class of drugs known as sulfones. It works by decreasing swelling (inflammation) and stopping the growth of bacteria.

This medication will not work for viral infections (such as common cold, flu). Unnecessary use or misuse of any antibiotic can lead to its decreased effectiveness.

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This drug may also be used for skin conditions in certain immune system disorders (such as systemic lupus erythematosus-SLE) or for a certain lung infection due to HIV (pneumocystis pneumonia). It may also be used to reduce the risk of a certain brain infection due to HIV (toxoplasmosis).

Take this medication by mouth with or without food as directed by your doctor, usually once daily.

Medications for heartburn/reducing stomach acid (such as large amounts of antacids, ranitidine, famotidine) may prevent full absorption of dapsone into your bloodstream, possibly reducing its effectiveness. Separate your dose of dapsone from your doses of any of these products by at least 2 hours. Ask your doctor or pharmacist for more details.

If you are taking dapsone for a skin disorder, your doctor may start you on a low dose of dapsone and gradually adjust your dose to control your disease. If you are taking this medication to treat Hansen's disease or to prevent infections due to HIV, the drug is usually taken for years or for life.

The dosage is based on your medical condition and response to treatment. Children's dosage is also based on age and weight.

For the best effect, take this antibiotic at evenly spaced times. To help you remember, take this medication at the same time(s) every day.

Tell your doctor if your condition gets worse.

Nausea, vomiting, loss of appetite, dizziness, or blurred vision may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have any serious side effects, including:

• unusually fast heartbeat
• unusually fast breathing
• bluish lips/skin
• chest pain
• mental/mood changes
• muscle weakness
• difficulty urinating

This drug may rarely cause very serious low blood counts (bone marrow suppression) or liver disease. Get medical help right away if you develop signs of an infection (such as sore throat that doesn't go away, fever, chills), easy bruising/bleeding, unusual tiredness, pale skin, yellowing eyes/skin, dark urine, stomach/abdominal pain.

Dapsone can commonly cause a rash that is usually not serious. However, you may not be able to tell it apart from a rare rash that could be a sign of a severe reaction. Get medical help right away if you develop any rash.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Before taking dapsone, tell your doctor or pharmacist if you are allergic to it; or to similar drugs such as sulfoxone; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• certain blood disorders (such as anemia, G6PD deficiency, methemoglobin reductase deficiency)
• liver disease
• heart disease
• lung disease
• serious infection
• very high blood sugar (diabetic ketosis)

If using this drug to treat Hansen's disease, note that as your immune system helps fight the infection, you may notice skin sores worsening, and numbness/pain/tingling or muscle weakness. This may require special treatment, so tell your doctor right away if these symptoms occur.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This medication passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug are:

• folic acid antagonists (such as pyrimethamine)
• nitrofurantoin
• primaquine

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669. Symptoms of overdose may include: seizures, bluish skin (cyanosis), sudden vision changes, sudden loss of vision.

Do not share this medication with others.

Lab and/or medical tests (such as complete blood counts/platelets, liver function) should be done while you are taking this medication. Keep all medical and lab appointments. Consult your doctor for more details.

Iron, folic acid, and vitamin C might reduce the risk of developing a certain serious side effect (anemia). Ask your doctor for more details.

If you are using dapsone for dermatitis herpetiformis, a gluten-free diet may improve the condition. Consult your doctor for more information.

If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.