Bactrim
® (
sulfamethoxazole/trimethoprim) is a prescription antibiotic approved to treat a variety of different infections. In addition to treating infections, it is also approved to prevent one particular infection,
Pneumocystis carinii pneumonia, in people with a weakened immune system.
(Click Bactrim Uses for more information on what the medication is used for, including possible off-label uses.)
Brand-name Bactrim is manufactured by Mutual Pharmaceutical Company, Inc. and is marketed and distributed by AR Scientific. Generic versions are made by various different manufacturers.
Bactrim contains two different antibiotics, sulfamethoxazole and trimethoprim. Sulfamethoxazole belongs to a group of drugs known as sulfonamides ("sulfa" drugs). Trimethoprim does not belong to a specific class of medications. These two antibiotics work in different but similar ways. Essentially, both sulfamethoxazole and trimethoprim work by inhibiting the production of
folic acid in bacteria, although they work in different stages of folic acid production. Folic acid is important for making proteins and DNA. Because humans obtain folic acid from the diet (and bacteria cannot), human cells are less affected by Bactrim.
Combining sulfamethoxazole with trimethoprim increases the effectiveness and decreases the chance of antibiotic resistance (when bacteria develop the ability to resist antibiotics).
When and How to Take Bactrim
Some general considerations include the following:
- Bactrim comes in tablet form. It is taken by mouth, usually twice a day (although it is taken as frequently as four times daily or as infrequently as once daily for certain uses).
- You can take this medication with food or on an empty stomach. If it bothers your stomach, try taking it with food.
- Bactrim can be taken at any time of the day; however, be sure to take the medication at the same time(s) each day. For instance, if you take it twice daily, it is best to evenly space the doses, taking a dose every 12 hours.
- For the medication to work properly, it must be taken as prescribed. Bactrim will not work if you stop taking it too soon.
The dose of Bactrim that your healthcare provider recommends will vary depending on a number of factors, including:
- The type of infection and bacteria
- Your height and weight (for some uses)
- Other medical conditions you may have
- Other medications you may currently be taking.
As is always the case, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
As with any medicine, side effects are possible. However, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. Serious side effects are less common.
Some of the common side effects include, but are not limited to:
- Nausea
- Vomiting
- Loss of appetite
- Rashes
- Itching.
(Click Bactrim Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
What Should I Tell My Healthcare Provider Before Taking Bactrim?
You should talk with your healthcare provider prior to taking this medication if you have:
- Anemia
- Asthma
- Glucose-6-phosphate dehydrogenase deficiency
- A folic acid deficiency
- Phenylketonuria (PKU)
- A thyroid disorder
- Porphyria
- HIV or AIDS
- Kidney disease, such as kidney failure (renal failure)
- Liver disease, such as liver failure, cirrhosis, or hepatitis
- Any other allergies, including allergies to food, dyes, or preservatives.
Also, let your healthcare provider know if you are:
Make sure to tell your healthcare provider about all other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
What If I Take an Overdose?
People who take an overdose may experience effects such as:
- Loss of appetite
- Abdominal pain
- Nausea
- Vomiting
- Dizziness
- Headache
- Drowsiness
- Unconsciousness
- Fever
- Blood in the urine
- Yellow skin (jaundice)
- Confusion.
If you happen to overdose on Bactrim, seek medical attention immediately.
What Should I Do If I Miss a Dose?
If you do not take your Bactrim as scheduled, take your missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose. Try not to miss doses, as this increases the risk of developing an antibiotic-resistant infection.
Bactrim comes in the following strengths:
- Bactrim tablets -- 80 mg of trimethoprim and 400 mg of sulfamethoxazole
- Bactrim DS ("double strength") tablets -- 160 mg of trimethoprim and 800 mg of sulfamethoxazole.
Store Bactrim at room temperature, away from moisture and heat. Be sure to keep it in an airtight container. Keep this and all medications out of the reach of children.
Generic Availability of Bactrim
Currently, this medication is available in generic form.
