Sulfamethoxazole Trimethoprim

Bactrim is the brand name of the generic antibiotic sulfamethoxazole trimethoprim (sometimes called co-trimoxazole).

The drug is a combination of two antibiotics: It's one part trimethoprim (a synthetic drug), and five parts sulfamethoxazole (a sulfonamide drug).

Bactrim works against bacteria in the following types of infections:

• Urinary tract infections (UTIs) caused by E. coli, Klebsiella, Enterobacter, Morganella morganii, Proteus mirabilis, and Proteus vulgaris
• Middle-ear infections (acute otitis media) in children if they're caused by the bacteria Streptococcus pneumoniae and Haemophilus influenzae
• Chronic bronchitis when it worsens (acute exacerbations) and is caused by Streptococcus pneumoniae or Haemophilus influenzae
• Some types of diarrhea, including dysentery, caused by Shigella flexneri and S. sonnei infections; and traveler's diarrhea, caused by enterotoxigenic E. coli
• Pneumonia caused by Pneumocystis jiroveci: for treatment, and sometimes for prevention when your immune system is compromised by immunosuppressant drugs or HIV/AIDS

Bactrim is also sometimes prescribed for other types of bacterial pneumonia, for acne, and for preventing urinary tract infections.

The Food and Drug Administration (FDA) first approved Bactrim in 1973. The drug is made by Mutual Pharmaceutical Co.

Bactrim Warnings

Bactrim shouldn't be used by people who:

• Are hypersensitive to trimethoprim or sulfonamide drugs (or have sulfa allergies)
• Have suffered from thrombocytopenia (low blood platelet count) after taking trimethoprim or sulfonamides
• Have megaloblastic anemia (low red blood cell count) caused by a folic acid deficiency
• Are less than two months old
• Have severe liver damage or poor kidney function that cannot be monitored

Though rare, the use of sulfonamides can cause severe and potentially fatal reactions, such as Stevens-Johnson syndrome.

Stop taking Bactrim and call your doctor right away if you develop a rash after taking Bactrim, and get emergency medical help if the rash starts to become severe or you feel like you are having an allergic reaction.

Other rare but serious reactions have included toxic epidermal necrolysis (a life-threatening skin condition), acute liver failure, agranulocytosis (severely low levels of white blood cells), aplastic anemia (when the body stops blood cell production), and other blood-related disorders.

As with most other antibiotics, Bactrim may cause prolonged diarrhea resulting from a difficult-to-treat Clostridium difficile (C. diff) infection.

Before taking Bactrim, also tell your doctor if you have:

• Folic acid deficiency
• Kidney or liver disease
• Severe allergies
• Bronchial asthma
• An inherited blood disease called glucose-6-phosphate dehydrogenase (G-6-PD) deficiency
• A thyroid disorder
• Porphyria, an inherited enzyme disease that may cause skin and nervous system problems
• HIV/AIDS
• Phenylketonuria, an inherited disorder that can cause intellectual disabilities if a strict diet is not maintained

Pregnancy and Bactrim

Bactrim may harm a developing fetus.

The drug has a warning that if you take it when you're pregnant, it can cause such birth defects as urinary tract defects, cleft lip or palate, or club feet.

Before taking Bactrim, tell your doctor if you are pregnant or may become pregnant.

It should only be used during pregnancy if the benefits clearly outweigh the potential harms to the unborn child.

You should not breastfeed when taking Bactrim. The drug is excreted in breast milk and has the potential to harm breastfeeding infants, especially if they are ill, stressed, or premature.

The most common side effect of Bactrim is nausea. Call your doctor if it worsens or does not go away, or if you experience:

• Stomach ache
• Vomiting
• Anorexia, or loss of appetite

Some other common side effects might be an early sign of a more severe reaction, so if you experience the following, stop taking the drug and call your doctor right away:

• Itchiness
• Rash
• Hives

Bactrim is associated with numerous rare side effects. Although they are not likely to require medical attention, you should tell your doctor if you have:

• Headache
• Abdominal pain or diarrhea
• Insomnia
• Mild tiredness
• Mild weakness

Serious Side Effects of Bactrim

Tell your doctor right away or get emergency medical help if you experience:

• Sore throat and cough
• Severe, prolonged diarrhea that may occur with fever and stomach cramps, which possibly indicates a C. difficile infection
• Fever or chills
• Trouble breathing
• Unusual bruising or bleeding
• Yellowing of the skin and eyes (jaundice)
• Joint or muscle pain
• Spots on the skin that are purple or reddish (purpura)
• Paleness
• Depression

G6PD is an enzyme in your body that is responsible for helping red blood cells to work properly. Some patients are born with less of this enzyme in their bodies, leading to the destruction of red blood cells. When sulfamethoxazole/trimethoprim is used in patients with G6PD deficiency, they have a higher chance of experiencing hemolytic anemia (a condition in which the body does not have enough red blood cells to deliver oxygen to your tissues).

G6PD testing may be done to determine whether you are at a higher risk of experiencing hemolytic anemia if you are to be treated with sulfamethoxazole/trimethoprim.

Your doctor will select an alternative medication as sulfamethoxazole/trimethoprim should not be given to patients with G6PD deficiency.

Sulfamethoxazole/trimethoprim is a prescription medication used to treat bacterial infections of the urinary tract, lungs, intestines, ears, and infections that cause traveler’s diarrhea.

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.

Sulfamethoxazole & Trimethoprim may be found in some form under the following brand names:

• Azo Gantanol

• Bactrim

• Bethaprim

• Cofatrim Fort

• Cotrim

• Gantanol

• Maracyn Plus

• Polytrim

• Primsol

• Proloprim

• Septra

• Sulfatrim

• Trimpex

• Tucoprim

• Uniprim

• Uroplus

If you take too much sulfamethoxazole/trimethoprim, call your healthcare provider or local Poison Control Center, or seek emergency medical attention right away.

Take sulfamethoxazole/trimethoprim 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 sulfamethoxazole/trimethoprim for the full time of treatment, even if you begin to feel better after a few days. If you stop taking sulfamethoxazole/trimethoprim too soon, your symptoms may return.

Dosing

The dose of sulfamethoxazole/trimethoprim 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/trimethoprim. 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 sulfamethoxazole/trimethoprim, 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.

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

Using sulfamethoxazole/trimethoprim 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, sulfamethoxazole/trimethoprim 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 sulfamethoxazole/trimethoprim 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.

sulfamethoxazole/trimethoprim, 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.

sulfamethoxazole/trimethoprim may cause diarrhea, and in some cases it can be severe. It may occur 2 months or more after you stop taking sulfamethoxazole/trimethoprim. 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.

sulfamethoxazole/trimethoprim 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.

sulfamethoxazole/trimethoprim 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 sulfamethoxazole/trimethoprim: 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 sulfamethoxazole/trimethoprim. The results of some tests may be affected by sulfamethoxazole/trimethoprim.

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 sulfamethoxazole/trimethoprim 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.