Rifampin is an antibiotic that is used to treat or prevent tuberculosis (TB).

Rifampin may also be used to reduce certain bacteria in your nose and throat that could cause meningitis or other infections. Rifampin prevents you from spreading these bacteria to other people, but this medicine will not treat an active meningitis infection.

Rifampin may also be used for purposes not listed in this medication guide.

You should not use this medicine if you are allergic to rifampin or similar medicines such as rifabutin, rifapentine, rifamycin, or rifaximin.

Many drugs can interact and cause dangerous effects. Some drugs should not be used together with rifampin. Your doctor may change your treatment plan if you also use: atazanavir, darunavir, fosamprenavir, praziquantel, ritonavir, saquinavir, or tipranavir.

Tell your doctor if you have ever had:

• diabetes;
• liver disease;
• bleeding problems; or
• porphyria (a genetic enzyme disorder that causes symptoms affecting the skin or nervous system).

It is not known whether this medicine will harm an unborn baby. However, using rifampin during the last few weeks of pregnancy may cause bleeding in the mother or the newborn baby. Tell your doctor if you are pregnant.

Rifampin can make hormonal birth control less effective, including birth control pills, injections, implants, skin patches, and vaginal rings. To prevent pregnancy while using rifampin, use a barrier form of birth control: condom, diaphragm, cervical cap, or contraceptive sponge.

You should not breastfeed while using this medicine.

Use Rifadin (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction (hives, rash, feeling light-headed, wheezing, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

Call your doctor at once if you have:

• severe stomach pain, diarrhea that is watery or bloody;
• chest pain, cough, shortness of breath;
• a light-headed feeling, like you might pass out;
• easy bruising, unusual bleeding (nosebleeds, bleeding gums);
• pounding heartbeats or fluttering in your chest;
• flu symptoms--fever, chills, body aches, headache, weakness, nausea, vomiting; or
• liver problems--upper stomach pain, tiredness, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes).

Common side effects may include:

• red discoloration of your teeth, sweat, urine, saliva, and tears;
• heartburn, gas, upset stomach, loss of appetite;
• nausea, vomiting, diarrhea;
• fever;
• headache, dizziness, drowsiness, tiredness;
• muscle weakness, pain in your arms or legs;
• problems with balance or muscle movement;
• numbness; or
• confusion, changes in behavior, trouble concentrating.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Avoid drinking alcohol. It may increase your risk of liver damage.

Avoid wearing contact lenses. Rifampin may discolor your tears, which could permanently stain soft contact lenses.