Bactrim, Septra (sulfamethoxazole / trimethoprim)

Antifolate / Sulfa Antibiotic Combinations

SULFAMETHOXAZOLE; TRIMETHOPRIM or SMX-TMP (suhl fuh meth OK suh zohl; trye METH oh prim) is a combination of a sulfonamide antibiotic and a second antibiotic, trimethoprim. It is used to treat or prevent certain kinds of bacterial infections. It will not work for colds, flu, or other viral infections.


Commonly Used Brand Name(s): Bactrim, Bactrim DS, Septra, Septra DS, SMZ-TMP Pediatric, Sulfatrim, Sulfatrim Pediatric, Apo-Sulfatrim, Novo-Trimel, Nu-Cotrimox, Septa Pediatric, Septra Pediatric Suspension

Therapeutic Classification: Sulfonamide Combination

Pharmacologic Classification: Folic Acid Antagonist

Chemical Classification: Sulfonamide

Sulfamethoxazole and trimethoprim combination is used to treat infections such as urinary tract infections, middle ear infections (otitis media), bronchitis, traveler's diarrhea, and shigellosis (bacillary dysentery). This medicine is also used to prevent or treat Pneumocystis jiroveci pneumonia or Pneumocystis carinii pneumonia (PCP), a very serious kind of pneumonia. This type of pneumonia occurs more commonly in patients whose immune systems are not working normally, such as cancer patients, transplant patients, and patients with acquired immune deficiency syndrome (AIDS).

Sulfamethoxazole and trimethoprim combination is an antibiotic. It works by eliminating the bacteria that cause many kinds of infections. This medicine will not work for colds, flu, or other virus infections.

This medicine is available only with your doctor's prescription.

Take this medicine exactly as directed by your doctor. Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered. To do so may increase the chance of side effects.

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. .

For patients taking the oral liquid, 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 using 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.

Dosing

The dose of this medicine 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 this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine 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 using the medicine.

  • For oral dosage forms (liquid or tablets):
    • For treatment of bacterial infections:
      • Adults and children weighing 40 kilograms (kg) or more—800 milligrams (mg) of sulfamethoxazole and 160 mg of trimethoprim every 12 hours for 10 to 14 days. Your doctor may adjust this dose if needed.
      • Children 2 months of age and older, and weighing up to 40 kg—Dose is based on body weight and must be determined by your doctor. The usual dose is 40 milligrams (mg) per kilogram of body weight of sulfamethoxazole and 8 milligrams (mg) per kilogram of body weight of trimethoprim, given in two divided doses every 12 hours for 10 days.
      • Infants younger than 2 months of age—Use is not recommended.
    • For treatment of Pneumocystis jiroveci pneumonia or Pneumocystis carinii pneumonia (PCP):
      • Adults and children 2 months of age and older—Dose is based on body weight and must be determined by your doctor. The usual dose is 75 to 100 milligrams (mg) per kilogram of body weight of sulfamethoxazole and 15 to 20 milligrams (mg) per kilogram of body weight of trimethoprim each day, given in equally divided doses every 6 hours for 14 to 21 days.
      • Children younger than 2 months of age—Use is not recommended.
    • For prevention of Pneumocystis jiroveci pneumonia or Pneumocystis carinii pneumonia (PCP):
      • Adults—800 milligrams (mg) of sulfamethoxazole and 160 mg of trimethoprim once a day.
      • Children 2 months of age and older—Dose is based on body size and must be determined by your doctor. The usual dose is 750 mg of sulfamethoxazole and 150 mg of trimethoprim per square meter (m[2]) of body surface each day. This is given in equally divided doses two times a day for 3 days a week on consecutive days (eg, Monday, Tuesday, Wednesday). However, the dose is usually not more than 1600 mg of sulfamethoxazole and 320 mg of trimethoprim per day.
      • Children younger than 2 months of age—Use is not recommended.
    • For traveler's diarrhea:
      • Adults—800 milligrams (mg) of sulfamethoxazole and 160 mg of trimethoprim every 12 hours for 5 days.
      • Children 2 months of age and older—Use and dose must be determined by your doctor.
      • Children younger than 2 months of age—Use is not recommended.

Missed Dose

If you miss a dose of this medicine, take it as soon as possible. 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.

Storage

Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.

Keep out of the reach of children.

Do not keep outdated medicine or medicine no longer needed.

Ask your healthcare professional how you should dispose of any medicine you do not use.

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 this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of sulfamethoxazole and trimethoprim combination in children 2 months of age and older. Because of the toxicity of the combination of sulfamethoxazole and trimethoprim, use in infants younger than 2 months of age is not recommended.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of sulfamethoxazole and trimethoprim combination in the elderly. However, elderly patients are more likely to have a folate deficiency, age-related kidney or liver problems, and may be more likely to experience unwanted side effects (eg, severe skin rash, increased potassium in the body, or problems with blood clotting or the immune system). There may be an adjustment in the dose for elderly patients receiving sulfamethoxazole and trimethoprim combination.

Pregnancy

Pregnancy CategoryExplanation
All TrimestersDStudies in pregnant women have demonstrated a risk to the fetus. However, the benefits of therapy in a life threatening situation or a serious disease, may outweigh the potential risk.

Breast Feeding

Studies in women suggest that this medication poses minimal risk to the infant when used during breastfeeding.

Drug Interactions

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 this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

  • Bepridil
  • Cisapride
  • Dofetilide
  • Levomethadyl
  • Mesoridazine
  • Methenamine
  • Pimozide
  • Terfenadine
  • Thioridazine

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Other Interactions

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following is usually not recommended, but may be unavoidable in some cases. If used together, your doctor may change the dose or how often you use this medicine, or give you special instructions about the use of food, alcohol, or tobacco.

  • Ethanol

Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

  • Alcohol abuse, history of or
  • Folate (vitamin B9) deficiency or
  • HIV or AIDS or
  • Kidney disease or
  • Liver disease or
  • Malabsorption syndrome (difficulty of absorbing food in the body) or
  • Malnutrition state (nutrition disorder)—Use with caution. May have an increased chance of serious side effects.
  • Anemia, megaloblastic (caused by low levels of folic acid in the body) or
  • Drug-induced thrombocytopenia (low platelets in the blood) after using this medicine or
  • Kidney disease, severe or
  • Liver disease, severe—Should not be used in patients with these conditions.
  • Asthma or
  • Diabetes or
  • Hyperkalemia (high potassium in the blood) or
  • Hyponatremia (low sodium in the blood) or
  • Porphyria (enzyme problem) or
  • Severe allergies or
  • Thyroid problems—Use with caution. May make these conditions worse.
  • Glucose-6-phosphate dehydrogenase (G6PD) deficiency (an enzyme problem)—May cause hemolytic anemia (blood disorder) in patients with this condition.
  • Streptococcal infection (group A β-hemolytic)—Sulfonamides should not be used in patients with this condition.

It is very important that your doctor check the progress of you or your child at regular visits to make sure that this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.

Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away.

Very rarely, this medicine has caused severe side effects. If you or your child start to have a skin rash, or if you think you are having a severe skin reaction, stop taking this medicine and call your doctor right away. Symptoms of a severe reaction may include a skin rash, skin color that is very pale or yellow, or skin with purple spots, along with a sore throat, fever, muscle pain, cough, and trouble with breathing.

This medicine, especially if you are receiving high doses or for a long period of time, may lower the number of platelets in your body, which are necessary for proper blood clotting. Because of this, you may bleed or get infections more easily. Talk with your doctor if you have concerns about this.

This medicine may cause diarrhea, and in some cases it can be severe. It may occur 2 months or more after you stop taking this medicine. Do not take any medicine to treat diarrhea without first checking with your doctor. If you have any questions or if mild diarrhea continues or gets worse, check with your doctor.

Check with your doctor right away if you or your child have abdominal or stomach cramps, bloating, watery and severe diarrhea, which may also be bloody, nausea or vomiting, or unusual tiredness or weakness. These may be symptoms of a serious intestinal infection.

This medicine may cause serious allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Check with your doctor right away if you or your child have a rash, itching, swelling of the face, tongue, and throat, trouble breathing, shortness of breath, or chest pain after you use the medicine.

This medicine may cause electrolyte problems, such as high potassium in the blood (hyperkalemia) and low sodium in the blood (hyponatremia). Tell your doctor right away if you have any of the following symptoms while using this medicine: confusion, weakness, muscle twitching, an irregular heartbeat, numbness or tingling in the hands, feet, or lips, or trouble breathing.

Before you have any medical tests, tell the medical doctor in charge that you or your child are taking this medicine. The results of some tests may be affected by this medicine.

Patients receiving anticonvulsant therapy (medicines to prevent seizures) may be at risk for a folate (vitamin B9) deficiency, which may increase the risk for side effects. Talk with your doctor if you have concerns about this.

Do not use this medicine for Pneumocystis jiroveci pneumonia (PCP) if you are also using leucovorin. Using these medicines together may cause these medicines to not work as well for you.

Do not take other medicines unless they have been discussed with your doctor. This includes leucovorin, other prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.

They need to know if you have any of these conditions:

  • anemia
  • asthma
  • being treated with anticonvulsants
  • if you frequently drink alcohol containing drinks
  • kidney disease
  • liver disease
  • low level of folic acid or glucose-6-phosphate dehydrogenase
  • poor nutrition or malabsorption
  • porphyria
  • severe allergies
  • thyroid disorder
  • an unusual or allergic reaction to sulfamethoxazole, trimethoprim, sulfa drugs, other medicines, foods, dyes, or preservatives
  • pregnant or trying to get pregnant
  • breast-feeding

Take this medicine by mouth with a full glass of water. Follow the directions on the prescription label. Take your medicine at regular intervals. Do not take it more often than directed. Do not skip doses or stop your medicine early.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed. This medicine has been used in children as young as 2 months of age.

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

Keep out of the reach of children.

Store at room temperature between 20 to 25 degrees C (68 to 77 degrees F). Protect from light. Throw away any unused medicine after the expiration date.

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