This medication is used alone or with another medication to help prevent a certain serious infection (Mycobacterium avium complex-MAC). Rifabutin is known as a rifamycin antibiotic. It works by stopping the growth of bacteria.

This antibiotic treats and prevents only bacterial infections. It will not work for viral infections (such as common cold, flu). Using any antibiotic when it is not needed can cause it to not work for future infections.

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 active MAC infection or active tuberculosis (TB) infection. It may also be used to reduce the risk of active TB infections in people who may be infected with the bacteria (people with positive TB skin test).

Take this medication by mouth with or without food as directed by your doctor, usually once or twice daily. Take this medication with food if stomach upset occurs. For the treatment of tuberculosis, this drug is sometimes taken twice weekly.

The dosage is based on your medical condition, weight, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

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.

Continue to take this medication until the full prescribed amount is finished, even if symptoms disappear. Stopping the medication too early or skipping doses may result in a return of the infection and cause the infection to be more difficult to treat (resistant).

Tell your doctor if your condition lasts or gets worse.

Diarrhea, stomach upset, changes in taste, or nausea/vomiting may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

This medication may cause urine, sweat, saliva, or tears to turn brown-orange. This effect is harmless and will disappear when the medication is stopped. However, dentures and contact lenses may be permanently stained.

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:

• nausea/vomiting that doesn't stop
• easy bleeding/bruising
• muscle weakness/pain
• joint pain/swelling
• eye pain/redness
• vision problems
• chest pain/pressure
• unusual weakness/tiredness
• dark urine
• yellowing eyes/skin

This medication may rarely cause a severe intestinal condition due to a bacteria called C. difficile. This condition may occur during treatment or weeks to months after treatment has stopped. Tell your doctor right away if you develop:

• diarrhea that doesn't stop
• abdominal or stomach pain/cramping
• blood/mucus in your stool

If you have these symptoms, do not use anti-diarrhea or opioid products because they may make symptoms worse.

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:

• fever that doesn't go away
• new or worsening lymph node swelling
• 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 rifabutin, tell your doctor or pharmacist if you are allergic to it; or to other rifamycins (such as rifampin); 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:

• kidney disease
• liver disease
• a certain blood disorder (porphyria)

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

Rifabutin may cause live bacterial vaccines (such as typhoid vaccine) to not work well. Tell your health care professional that you are using rifabutin before having any immunizations/vaccinations.

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

It is unknown if this medication passes into breast milk. If you have HIV, breast milk may transmit HIV. 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 include:

• azole antifungals (such as fluconazole, itraconazole, voriconazole)
• ciprofloxacin
• macrolide antibiotics (such as clarithromycin)

Rifabutin can speed up the removal of other medications from your body, which may affect how they work. Examples of affected drugs include aprepitant/fosaprepitant, lurasidone, mavacamten, phenytoin, ranolazine, suvorexant, tacrolimus, tasimelteon, "blood thinners" (such as warfarin), calcium channel blockers (such as diltiazem, verapamil), certain combination products used to treat chronic hepatitis C (ombitasvir/paritaprevir/ritonavir), among others.

This medication may decrease the effectiveness of hormonal birth control such as pills, patch, or ring. This could cause pregnancy. Discuss with your doctor or pharmacist if you should use reliable backup birth control methods while using this medication. Also tell your doctor if you have any new spotting or breakthrough bleeding, because these may be signs that your birth control is not working well.

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.

Do not share this medication with others.

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

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.