Bactrim (Sulfamethoxazole/Trimethoprim)

(℞) Prescription Required

    Bactrim (Sulfamethoxazole/Trimethoprim) Dosage and Side Effects

    Bactrim contains a combination of sulfamethoxazole and trimethoprim. Bactrim is used to treat ear infections, urinary tract infections, bronchitis, traveler's diarrhea, shigellosis, and Pneumocystis jiroveci pneumonia.

    Proper Use of medication

    Take exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. Follow the directions on your prescription label.

    Measure liquid medicine with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.

    Take this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Sulfamethoxazole and trimethoprim will not treat a viral infection such as the common cold or flu.

    Drink plenty of fluids to prevent kidney stones while you are taking trimethoprim and sulfamethoxazole.

    This medication can cause unusual results with certain medical tests. Tell any doctor who treats you that you are using sulfamethoxazole and trimethoprim.

    Store at room temperature away from moisture, heat, and light.

    Side Effects

    Nausea, vomiting, diarrhea, and loss of appetite may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

    Remember that your doctor has prescribed this medication because he or she 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: muscle weakness, mental/mood changes, blood in the urine, change in the amount of urine, extreme drowsiness, signs of low blood sugar (such as nervousness, shakiness, sweating, hunger).

    Get medical help right away if you have any very serious side effects, including: persistent headache, neck stiffness, seizures, slow/irregular heartbeat.

    This medication may rarely cause serious (possibly fatal) allergic reactions and other side effects such as a severe peeling skin rash (such as Stevens-Johnson syndrome), blood disorders (such as agranulocytosis, aplastic anemia), liver damage, or lung injury. If you notice any of the following, get medical help right away: skin rash/blisters, itching/swelling (especially of the face/tongue/throat), persistent sore throat or fever, paleness, joint pain/aches, persistent cough, trouble breathing, easy bleeding/bruising, yellowing eyes or skin, persistent nausea/vomiting, unusual fatigue, dark urine.

    This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a type of resistant bacteria. This condition may occur during treatment or weeks to months after treatment has stopped. Tell your doctor right away if you develop: persistent diarrhea, abdominal or stomach pain/cramping, blood/mucus in your stool.

    Do not use anti-diarrhea products or narcotic pain medications if you have any of these symptoms because these products may make them worse.

    Use of this medication for prolonged or repeated periods may result in oral thrush or a new yeast infection. Contact your doctor if you notice white patches in your mouth, a change in vaginal discharge, or other new symptoms.

    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.

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

    Warnings and Precautions

    You should not use this medication if you are allergic to sulfamethoxazole or trimethoprim, if you are pregnant or breast-feeding, or if you have anemia (lack of red blood cells) caused by folic acid deficiency.

    Before using this medication, tell your doctor if you have kidney or liver disease, a folic acid deficiency, asthma or severe allergies, a thyroid disorder, HIV or AIDS, porphyria, G6PD deficiency, or if you are malnourished.

    Take this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Sulfamethoxazole and trimethoprim will not treat a viral infection such as the common cold or flu.

    Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or has blood in it, call your doctor. Do not use any medicine to stop the diarrhea unless your doctor has told you to.

    Avoid exposure to sunlight or tanning beds. This medication can make you sunburn more easily. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

    Interactions with the medication

    Tell your doctor about all other medications you use, especially:

    • an antidepressant;
    • a blood thinner such as warfarin (Coumadin, Jantoven);
    • cyclosporine (Gengraf, Neoral, Sandimmune);
    • oral diabetes medication;
    • digoxin (Lanoxin, Lanoxicaps);
    • a diuretic (water pill);
    • indomethacin (Indocin);
    • leucovorin, calcium folinate;
    • methotrexate (Trexall, Rheumatrex);
    • heart or blood pressure medication such as benazepril (Lotensin), captopril (Capoten), fosinopril (Monopril), enalapril (Vasotec), lisinopril (Prinivil, Zestril), moexipril (Univasc), perindopril (Aceon), quinapril (Accupril), ramipril (Altace), or trandolapril (Mavik).
    • seizure medication such as phenytoin (Dilantin);

    This list is not complete and other drugs may interact with sulfamethoxazole and trimethoprim. Tell your doctor about all medications you use. This includes prescription, over-the-counter, vitamin, and herbal products. Do not start a new medication without telling your doctor.

    Other related products

    The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

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