Medically reviewed by Jessica Swirble, PharmD
Last updated on March 27, 2025
Drug Information | Side Effects | Use & Dosage | Request an Online Prescription
Bactrim is a combination antibiotic medication that contains sulfamethoxazole and trimethoprim. It is commonly prescribed to treat bacterial infections such as urinary tract infections, respiratory tract infections, traveler's diarrhea, and certain types of pneumonia.
Bactrim is used to treat conditions such as:
It may also be prescribed for other bacterial infections as determined by your healthcare provider.
Bactrim works by inhibiting the production of folic acid in bacteria, which is essential for their growth and survival. By blocking this process, Bactrim effectively kills or stops the growth of bacteria causing the infection.
Bactrim is typically taken orally, with a full glass of water, as directed by your healthcare provider. It can be taken without food. However, taking Bactrim with food or milk may prevent stomach upset and irritation. It is important to follow the prescribed dosage and schedule. Do not skip doses or stop taking Bactrim before completing the full course, even if you feel better.
Consult your healthcare provider for specific instructions on how to take Bactrim properly.
The time it takes to experience improvement in symptoms while taking Bactrim can vary depending on the type and severity of the infection. Some people may start feeling better within a few days, while others may require the full course of treatment to see significant results. It's crucial to complete the prescribed course of Bactrim as directed.
While Bactrim is primarily used for bacterial infections, healthcare providers may sometimes prescribe it off-label for other conditions, such as:
Discuss any alternative uses of Bactrim with your healthcare provider.
Bactrim is available in its generic form (sulfamethoxazole-trimethoprim) in the following dosage forms:
The brand name Bactrim has been discontinued. You can only get this medication in its generic form.
Bactrim is a prescription medication. You will need a valid prescription from a licensed healthcare provider to obtain this drug.
The use of Bactrim has been shown to cause side effects in some patients.
Common mild side effects of Bactrim use include:
More severe side effects include:
Seek medical attention immediately if you experience any severe symptoms while taking Bactrim. If you experience mild side effects that become severe or do not go away after a few days, speak to a healthcare provider right away.
Before starting treatment with Bactrim, tell your healthcare provider about any existing medical conditions, allergies, or other medications you are taking. This includes prescription drugs, over-the-counter medications, and dietary supplements, as they may interact with this drug.
Tell your provider if you are taking these medications or supplements:
You should also mention medical conditions such as:
If you are pregnant, planning to become pregnant, or breastfeeding, consult your healthcare provider before using Bactrim to assess potential risks and benefits.
You can follow your regular diet while taking Bactrim. Talk to your healthcare provider about the use of this drug with food, beverages, alcohol, and tobacco.
Your healthcare provider will provide specific instructions regarding the use of Bactrim with food, beverages, and other medications. It's essential to follow their guidance to ensure the effectiveness of the treatment and minimize the risk of side effects.
The symptoms of a Bactrim (sulfamethoxazole-trimethoprim) overdose include:
If you experience any of these symptoms, call the poison control helpline at 1-800-222-1222. If an individual has collapsed, is having seizures, or is unresponsive, call 9-1-1 immediately.
Bactrim is a combination antibiotic containing sulfamethoxazole and trimethoprim. It is available in various strengths, including:
The typical starting dose of Bactrim can vary depending on the specific infection being treated, the patient's age, weight, medical history, and other individual factors. It is crucial to follow your healthcare provider's instructions regarding dosage and administration carefully.
For the treatment of bacterial infections, the typical starting doses of Bactrim may be:
Bactrim should be taken with a full glass of water and may be taken with or without food. Taking Bactrim with food may help decrease stomach upset. It is essential to complete the full course of treatment prescribed by your healthcare provider, even if you start to feel better before finishing the medication.
Your healthcare provider will assess your medical history, current medications, and the nature of your infection to determine the most appropriate starting dose and duration of treatment for you.
If you have any questions about your dosage, potential side effects, or need adjustments, contact your healthcare provider for guidance. If you want to to talk to a provider right away, book an online doctor appointment through telehealth platforms like Sesame.
If you miss a dose, take it as soon as you remember it. If it's almost time for another dose of Bactrim, skip the missed dose and take your next dose as scheduled. Do not take or apply a double dose of Bactrim.
Do not discontinue or alter your Bactrim dosage without consulting with your healthcare provider. Follow your healthcare provider's instructions regarding dosing and other recommendations for taking Bactrim.
Store Bactrim as directed by your healthcare provider or pharmacist. Proper storage is essential to maintain the medication's effectiveness. Bactrim should be stored at room temperature, away from excessive heat, light, and moisture.
Keep the medication out of the reach of children and ensure that the container is tightly closed.