Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Mycobutin. If you are concerned about side effects, discuss the risks and benefits of Mycobutin with your doctor.

The following side effects have been reported by at least 1% of people taking Mycobutin. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• burping
• Diarrhea (mild)
• discolouration of spit, sweat, tears, or skin
• indigestion
• nausea
• skin rash
• stomach pain
• urine discoloration
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• joint or muscle pain
• loss of strength or energy
• symptoms of eye inflammation (eye pain, blurred vision, floating dark spots, redness, light sensitivity)
• symptoms of an infection (such as fever or chills, sore throat, headache, overall weakness)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• chest pain
• signs of a severe skin reaction such as blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort
• symptoms of antibiotic-associated diarrhea (severe, watery diarrhea that may be bloody)
• symptoms of active Tuberculosis (such as cough, fever, poor appetite, night sweats, and unintentional weight loss)
• symptoms of a Anaphylaxis (severe allergic reaction) (such as Hives, difficulty breathing, or swelling of the face and throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Mycobutin.

Each hard gelatin capsule with an opaque red-brown cap and body, imprinted with "PHARMACIA & UPJOHN/MYCOBUTIN" in white ink contains rifabutin 150 mg. Nonmedicinal ingredients: microcrystalline cellulose, magnesium stearate, red iron oxide, silica gel, sodium lauryl sulfate, titanium dioxide, and edible white ink.

Do not take Mycobutin if you:

• are allergic to rifabutin or any ingredients of Mycobutin
• are allergic to related medications (e.g., rifampin)

There may be an interaction between rifabutin and any of the following:

• Abiraterone
• alpha-blockers (e.g., Alfuzosin, Doxazosin, Silodosin, Tamsulosin)
• anticancer medications (e.g., Cabazitaxel, Docetaxel; Doxorubicin; Etoposide, Ifosfamide, Irinotecan, Temsirolimus, Vincristine)
• certain antipsychotic medications (e.g., Aripiprazole, Clozapine, Haloperidol, Quetiapine)
• Apalutamide
• Aprepitant
• atovaquone
• "azole" antifungal medications (e.g., fluconazole, itraconazole, ketoconazole,)
• BCG
• barbiturates (e.g., butalbital, pentobarbital, Phenobarbital)
• birth control pills
• Bosentan
• Buprenorphine
• Buspirone
• Calcitriol
• calcium channel blockers (e.g., Amlodipine, Diltiazem, Nifedipine, Verapamil)
• Carbamazepine
• chloroquine
• Citalopram
• Cobicistat
• conivaptan
• corticosteroids (e.g., Dexamethasone, Prednisone, Hydrocortisone)
• Cyclosporine
• Dapsone
• Deferasirox
• Diazepam
• Digoxin
• Disopyramide
• Dronedarone
• Elagolix
• Enzalutamide
• Eplerenone
• Escitalopram
• estrogens (e.g., conjugated estrogen, Estradiol, ethinyl estradiol)
• Everolimus
• Flibanserin
• Hepatitis C antivirals (e.g., elbasvir, glecaprevir and pibrentasvir, grazoprevir, letermovir, velpatasvir)
• HIV integrase inhibitors (e.g., bictegravir, elvitegravir)
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., doravirine, efavirenz, etravirine, nevirapine, rilpivirine)
• HIV nucleoside reverse transcriptase inhibitors (NRTIs; e.g., abacavir, lamivudine, tenofovir, zidovudine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• isoniazid
• Lansoprazole
• Lemborexant
• lidocaine
• Losartan
• lumacaftor and Ivacaftor
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• maraviroc
• Mefloquine
• Methadone
• Mirtazapine
• Modafinil
• mycophenolate
• Naloxegol
• narcotic pain relievers (e.g., Fentanyl, Morphine, Oxycodone)
• Ondansetron
• Perampanel
• phenobarbital
• Phenytoin
• praziquantel
• primidone
• Primaquine
• progestins (e.g., medroxyprogesterone acetate)
• protein kinase inhibitors (e.g., Bosutinib, Dabrafenib, Dasatinib, imatinib, Nilotinib)
• quinidine
• quinine
• Repaglinide
• rifampin
• Roflumilast
• Romidepsin
• St. John's wort
• Sarilumab
• siltuximab
• Sirolimus
• sodium picosulfate
• "statin" anti-cholesterol medications (e.g., Atorvastatin, Lovastatin, Simvastatin)
• sulfonylureas (e.g., Gliclazide, Glyburide, Tolbutamide)
• Tacrolimus
• Tamoxifen
• Tetracycline
• Ticagrelor
• Tocilizumab
• Tofacitinib
• Tolvaptan
• Tramadol
• Trazodone
• Triazolam
• tricyclic antidepressants (e.g., Amitriptyline, Imipramine, Nortriptyline)
• certain vaccines
• upadacitinib
• Warfarin
• Zolpidem
• Zopiclone

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Mycobutin. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use Mycobutin.

Antibiotic-associated diarrhea: Mycobutin, like other antibiotics, may cause a potentially dangerous condition called antibiotic-associated, or pseudomembranous, colitis. Symptoms include severe, watery diarrhea that may be bloody. If you notice these symptoms, stop taking rifabutin and contact your doctor as soon as possible.

Bacterial resistance: Misuse of an antibiotic such as rifabutin may lead to the growth of resistant bacteria that will not be killed by the antibiotic. If this happens, the antibiotic may not work for you in the future. Although you may begin to feel better when you first start taking rifabutin, you need to take all the medication exactly as directed by your doctor to finish ridding your body of the infection and to prevent resistant bacteria from taking hold. Do not take rifabutin or other antibiotics to treat a viral infection such as The Common Cold; antibiotics do not kill viruses, and using them to treat viral infections can lead to the growth of resistant bacteria.

Blood counts: Mycobutin can decrease the number of neutrophils (a type of white blood cell that helps fight infection), red blood cells (which carry oxygen), and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, contact your doctor immediately.

Body fluids: Urine may be coloured brown-orange while taking Mycobutin. Your stools, saliva, sputum, perspiration, and tears may also be affected.

Contact lenses: The colouring of body fluids to a reddish-brown colour may cause soft contact lenses to become permanently discoloured. Hard contact lenses are not affected.

Hypersensitivity reactions: In rare cases, Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS syndrome) may occur. This is more likely to occur for people who are taking medications to treat tuberculosis. This reaction may involve fever, swollen glands, yellowing of the skin or eyes, and flu-like symptoms with skin rash or blistering.,Get immediate medical attention if you have symptoms of a severe allergic reaction. If you experience any unusual symptoms, contact your doctor.

Kidney function: Kidney Disease or reduced kidney function may cause Mycobutin to build up in the body, causing side effects. If you have reduced kidney function or kidney disease, discuss with your doctor how Mycobutin may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Mycobutin, and whether any special monitoring is needed.

Liver function: Severe liver disease or reduced liver function may cause Mycobutin to build up in the body, causing side effects. If you have liver problems, discuss with your doctor how Mycobutin may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Mycobutin, and whether any special monitoring is needed. Your doctor may want to test your liver function regularly with blood tests while you are taking Mycobutin.

Tuberculosis: People with active tuberculosis should not use rifabutin. If you have this condition or suspect that you may have it (symptoms include cough, fever, poor appetite, night sweats, and unintentional weight loss), talk to your doctor.

Pregnancy: Mycobutin should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Mycobutin, contact your doctor immediately.

Breast-feeding: It is not known if rifabutin passes into breast milk. If you are a breast-feeding mother and are taking Mycobutin, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Mycobutin to prevent MAC infection have not been established for children under 18 years of age. Rifabutin has been used to treat MAC infection in a small number of children.