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Description

Sulfamethoxazole and trimethoprim (sul-fa-meth-OX-a-zole and trye-METH-oh-prim) combination is used to treat infections, such as bronchitis, middle ear infection, urinary tract infection, and traveler's diarrhea. It is also used for the prevention and treatment of Pneumocystis carinii pneumonia (PCP). It will not work for colds, flu, or other virus infections. It may also be used for other conditions as determined by your doctor.

Sulfamethoxazole and trimethoprim combination is available only with your doctor's prescription, in the following dosage forms:

Oral
• Oral suspension (U.S. and Canada)
• Tablets (U.S. and Canada)

Parenteral
• Injection (U.S. and Canada)

It is very important that you read and understand the following information. If any of it causes you special concern, check with your doctor. Also, if you have any questions or if want more information about this medicine or your medical problem, ask your doctor, nurse, or pharmacist.
Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sulfamethoxazole and trimethoprim combination, the following should be considered:

Allergies -- Tell your doctor if you have ever had any unusual or allergic reaction to sulfa medicines, furosemide (e.g., Lasix) or thiazide diuretics (water pills), oral antidiabetics (diabetes medicine you take by mouth), glaucoma medicine you take by mouth (for example, acetazolamide [e.g., Diamox], dichlorphenamide [e.g., Daranide], methazolamide [e.g., Neptazane]), or trimethoprim (e.g., Trimpex). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy -- Sulfamethoxazole and trimethoprim combination has not been reported to cause birth defects or other problems in humans. However, studies in mice, rats, and rabbits have shown that some sulfonamides cause birth defects, including cleft palate and bone problems. Studies in rabbits have also shown that trimethoprim causes birth defects, as well as a decrease in the number of successful pregnancies.

Breast-feeding -- Sulfamethoxazole and trimethoprim pass into the breast milk. This medicine is not recommended for use during breast-feeding. It may cause liver problems, anemia, and other unwanted effects in nursing babies, especially those with glucose-6-phosphate dehydrogenase (G6PD) deficiency.

Age Groups

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sulfamethoxazole and trimethoprim combination, the following should be considered:

Children -- This medicine should not be given to infants under 2 months of age unless directed by the child's doctor, because it may cause brain problems.

Older adults -- Elderly people are especially sensitive to the effects of sulfamethoxazole and trimethoprim combination. Severe skin problems and blood problems may be more likely to occur in the elderly. These problems may also be more likely to occur in patients who are taking diuretics (water pills) along with this medicine.

Other Therapy

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For sulfamethoxazole and trimethoprim combination, the following should be considered:

Other medicines -- Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking sulfamethoxazole and trimethoprim combination, it is especially important that your health care professional knows if you are taking any of the following:

• Acetaminophen (e.g., Tylenol) (with long-term, high-dose use) or
• Amiodarone (e.g., Cordarone) or
• Anabolic steroids (nandrolone [e.g., Anabolin], oxandrolone [e.g., Anavar], oxymetholone [e.g., Anadrol], stanozolol [e.g., Winstrol]) or
• Androgens (male hormones) or
• Antithyroid agents (medicine for overactive thyroid) or
• Carbamazepine (e.g., Tegretol) or
• Carmustine (e.g., BiCNU) or
• Chloroquine (e.g., Aralen) or
• Dantrolene (e.g., Dantrium) or
• Daunorubicin (e.g., Cerubidine) or
• Disulfiram (e.g., Antabuse) or
• Divalproex (e.g., Depakote) or
• Estrogens (female hormones) or
• Etretinate (e.g., Tegison) or
• Gold salts (medicine for arthritis) or
• Hydroxychloroquine (e.g., Plaquenil) or
• Mercaptopurine (e.g., Purinethol) or
• Naltrexone (e.g., Trexan) (with long-term, high-dose use) or
• Oral contraceptives (birth control pills) containing estrogens or
• Other anti-infectives by mouth or by injection (medicine for infection) or
• Phenothiazines (acetophenazine [e.g., Tindal], chlorpromazine [e.g., Thorazine], fluphenazine [e.g., Prolixin], mesoridazine [e.g., Serentil], perphenazine [e.g., Trilafon], prochlorperazine [e.g., Compazine], promazine [e.g., Sparine], promethazine [e.g., Phenergan], thioridazine [e.g., Mellaril], trifluoperazine [e.g., Stelazine], triflupromazine [e.g., Vesprin], trimeprazine [e.g., Temaril]) or
• Plicamycin (e.g., Mithracin) or
• Valproic acid (e.g., Depakene) -- Use of sulfamethoxazole and trimethoprim combination with these medicines may increase the chance of side effects affecting the liver

• Acetohydroxamic acid (e.g., Lithostat) or
• Dapsone or
• Furazolidone (e.g., Furoxone) or
• Nitrofurantoin (e.g., Furadantin) or
• Primaquine or
• Procainamide (e.g., Pronestyl) or
• Quinidine (e.g., Quinidex) or
• Quinine (e.g., Quinamm) -- Use of sulfamethoxazole and trimethoprim combination with these medicines may increase the chance of side effects affecting the blood

• Anticoagulants (blood thinners) or
• Ethotoin (e.g., Peganone) or
• Mephenytoin (e.g., Mesantoin) -- Use of sulfamethoxazole and trimethoprim combination with these medicines may increase the chance of side effects of these medicines

• Antidiabetics, oral (diabetes medicine you take by mouth) -- Use of oral antidiabetics with sulfamethoxazole and trimethoprim combination may increase the chance of side effects affecting the blood and/or the side effects of the oral antidiabetics

• Methenamine (e.g., Mandelamine) -- Use of methenamine with sulfamethoxazole and trimethoprim combination may increase the chance of side effects of the sulfamethoxazole

• Methotrexate (e.g., Mexate) or
• Phenytoin (e.g., Dilantin) -- Use of these medicines with sulfamethoxazole and trimethoprim combination may increase the chance of side effects affecting the liver and/or the side effects of these medicines

• Methyldopa (e.g., Aldomet) -- Use of methyldopa with sulfamethoxazole and trimethoprim combination may increase the chance of side effects affecting the liver and/or the blood

Other medical problems -- The presence of other medical problems may affect the use of sulfamethoxazole and trimethoprim combination. Make sure you tell your doctor if you have any other medical problems, especially:

• Anemia or other blood problems or
• Glucose-6-phosphate dehydrogenase (G6PD) deficiency -- Patients with these problems may have an increase in side effects affecting the blood

• Kidney disease or
• Liver disease -- Patients with kidney and/or liver disease may have an increased chance of side effects

• Porphyria -- This medicine may bring on an attack of porphyria

Before you begin using any new medicine (prescription or nonprescription) or if you develop any new medical problem while you are using this medicine, check with your doctor, nurse, or pharmacist.
Proper Use of This Medicine

Sulfamethoxazole and trimethoprim combination is best taken with a full glass (8 ounces) of water. Several additional glasses of water should be taken every day, unless otherwise directed by your doctor. Drinking extra water will help to prevent some unwanted effects of sulfonamides.

For patients taking the oral liquid form of this medicine:

• Use a specially marked measuring spoon or other device to measure each dose accurately. The average household teaspoon may not hold the right amount of liquid.

To help clear up your infection completely, keep taking this medicine for the full time of treatment, even if you begin to feel better after a few days. If you stop taking this medicine too soon, your symptoms may return.

This medicine works best when there is a constant amount in the blood or urine. To help keep the amount constant, do not miss any doses. Also, it is best to take the doses at evenly spaced times day and night. For example, if you are to take 4 doses a day, the doses should be spaced about 6 hours apart. If this interferes with your sleep or other daily activities, or if you need help in planning the best times to take your medicine, check with your health care professional.

Storage -- To store this medicine:

• Keep out of the reach of children.

• Store away from heat and direct light.

• Do not store the tablet form of this medicine in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.

• Keep the oral liquid form of this medicine from freezing.

• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

Dosing

Dosing -- The dose of sulfamethoxazole and trimethoprim combination will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of sulfamethoxazole and trimethoprim combination. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets or teaspoonfuls of suspension that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are taking sulfamethoxazole and trimethoprim combination.

• For oral dosage forms (suspension, tablets):

-- For bacterial infections:

• Adults and children over 40 kilograms (kg) of body weight (88 pounds) -- 160 milligrams (mg) of trimethoprim and 800 mg of sulfamethoxazole every twelve hours.

• Infants younger than 2 months of age -- Use and dose must be determined by your doctor.

• Infants 2 months of age and older and children up to 40 kg of weight (88 pounds) -- Dose is based on body weight. The usual dose is 4 to 6 mg of trimethoprim and 20 to 30 mg of sulfamethoxazole per kg (1.8 to 2.7 mg of trimethoprim and 9.1 to 13.6 mg of sulfamethoxazole per pound) of body weight every twelve hours.

-- For the treatment of Pneumocystis carinii pneumonia (PCP):

• Adults and children older than 2 months -- Dose is based on body weight. The usual dose is 3.75 to 5 mg of trimethoprim and 18.75 to 25 mg of sulfamethoxazole per kg (1.7 to 2.3 mg of trimethoprim and 8.5 to 11.4 mg of sulfamethoxazole per pound) of body weight every six hours.

-- For the prevention of Pneumocystis carinii pneumonia (PCP):

• Adults and teenagers -- 160 mg of trimethoprim and 800 mg of sulfamethoxazole one or two times a day.

• Infants and children 1 month of age and older -- Dose is based on body size and must be determined by your doctor. There are several dosing regimens available that your doctor may choose from. One dosing regimen is 75 mg of trimethoprim and 375 mg of sulfamethoxazole per square meter of body surface (m(sup 2)) three times a week on consecutive days (e.g., Monday, Tuesday, Wednesday).

• For injection dosage form:

-- For bacterial infections:

• Adults and children older than 2 months -- The usual total daily dose is 8 to 10 mg of trimethoprim and 40 to 50 mg of sulfamethoxazole per kg (3.6 to 4.5 mg of trimethoprim and 18.2 to 22.7 mg of sulfamethoxazole per pound) of body weight. This total daily dose may be divided up and injected into a vein every six, eight, or twelve hours.

• Infants younger than 2 months of age -- Use and dose must be determined by your doctor.

-- For the treatment of Pneumocystis carinii pneumonia (PCP):

• Adults and children older than 2 months -- The usual dose is 3.75 to 5 mg of trimethoprim and 18.75 to 25 mg of sulfamethoxazole per kg (1.7 to 2.3 mg of trimethoprim and 8.5 to 11.4 mg of sulfamethoxazole per pound) of body weight. This is injected into a vein every six hours.

• Infants younger than 2 months of age -- Use and dose must be determined by your doctor.

Missed dose -- If you miss a dose of this medicine, take it as soon as possible. This will help to keep a constant amount of medicine in the blood or urine. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Precautions While Using This Medicine

It is very important that your doctor check your progress at regular visits. This medicine may cause blood problems, especially if it is taken for a long time.

If your symptoms do not improve within a few days, or if they become worse, check with your doctor.

Sulfamethoxazole and trimethoprim combination may cause blood problems. These problems may result in a greater chance of certain infections, slow healing, and bleeding of the gums. Therefore, you should be careful when using regular toothbrushes, dental floss, and toothpicks. Dental work should be delayed until your blood counts have returned to normal. Check with your medical doctor or dentist if you have any questions about proper oral hygiene (mouth care) during treatment.

Sulfamethoxazole and trimethoprim combination may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin taking this medicine:

• Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.

• Wear protective clothing, including a hat. Also, wear sunglasses.

• Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.

• Apply a sun block lipstick that has an SPF of at least 15 to protect your lips.

• Do not use a sunlamp or tanning bed or booth.

If you have a severe reaction from the sun, check with your doctor.

This medicine may also cause some people to become dizzy. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert. If this reaction is especially bothersome, check with your doctor.

Side Effects of This Medicine

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

More common
Itching; skin rash

Less common
Aching of joints and muscles; difficulty in swallowing; pale skin; redness, blistering, peeling, or loosening of skin; sore throat and fever; unusual bleeding or bruising; unusual tiredness or weakness; yellow eyes or skin

Rare
Blood in urine; bluish fingernails, lips, or skin; difficult breathing; greatly increased or decreased frequency of urination or amount of urine; increased thirst; lower back pain; pain or burning while urinating; swelling of front part of neck

Also, check with your doctor as soon as possible if the following side effect occurs:

More common
Increased sensitivity of skin to sunlight

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

More common
Diarrhea; dizziness; headache; loss of appetite; nausea or vomiting

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Additional Information

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, sulfamethoxazole and trimethoprim combination is used in certain patients with the following medical conditions:

• Bile infections

• Bone and joint infections

• Sexually transmitted diseases, such as gonorrhea

• Sinus infections

• Urinary tract infections (for prevention)

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.

*This information is reproduced from the Mayo Clinic Family Pharmacist v 2.0
Copyright 1994-1995 IVI Publishing Inc.

This information may not be complete and/or up to date.  Please do not use this as any sort of authoritative text for this drug.  Please consult with a physician before taking this or any drug.  This is presented only for reference usage within this site.