Sulfamethoxazole 160 mg + Trimethoprim 800 mg

Category- Allopathy

Medicine Highlights

Sulfamethoxazole + Trimethoprim Uses  

Sulfamethoxazole + Trimethoprim is an oral antibiotic combination belonging to the sulfonamide and folate pathway inhibitor class. It is used to treat bacterial infections such as: 

1. Urinary tract infections (UTIs)  
2. Bronchitis or pneumonia caused by bacteria 
3. Ear infections (otitis media) 
4. Gastrointestinal infections   

Directions for use

1. Take this medicine exactly as prescribed by your doctor, at the same time each day. 
2. Do not stop taking this medicine without your doctor’s approval, even if you feel better. 
3. If you forget to take this medicine, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose.  

Sulfamethoxazole + Trimethoprim side effects 

More Common  

1. Redness or irritation of the skin 
2. Dryness or peeling 
3. Itching or burning sensation 
4. Mild rash 

Less Common

1. Severe allergic reaction (swelling, hives, trouble breathing) 
2. Severe skin rash or blistering    

How Sulfamethoxazole + Trimethoprim works 

This combination is an antibiotic that works by blocking bacteria from making folic acid, a vitamin they need to grow and multiply. Without folic acid, the bacteria cannot survive, which helps the body fight off the infection. 

Safety Measures and Warning 

Allergy/Hypersensitivity

Avoid if you are allergic to Sulfamethoxazole + Trimethoprim. Allergic reactions can be severe, including swelling, rashes, or breathing difficulties. Inform your doctor before taking it. 

Liver or kidney disease

The medicine is processed by the liver and kidneys. If these organs are damaged, your doctor must check if it’s safe, as the medicine can worsen liver or kidney function. 

Blood disorders (like low blood cell counts or anemia)

This medicine can sometimes affect blood cell production, so your doctor needs to monitor your blood before and during treatment. 

Pregnant or breastfeeding women

Use this medicine only if clearly needed, and doctor’s approval is necessary, as it can affect the baby. 

Sulfamethoxazole + Trimethoprim Interaction with Food Product

This medicine can be taken with or without food, but it’s best to take it with a full glass of water to avoid stomach upset. Avoid alcohol while on this medicine, as it may increase side effects. Always follow your doctor’s instructions for safe use.  

Sulfamethoxazole + Trimethoprim Interaction with Other Medicines

Avoid taking Sulfamethoxazole + Trimethoprim with the following medicines, as it may increase or decrease the desired effect, or in worse cases, it could be fatal: 

Sulfamethoxazole + Trimethoprim Chemical Structure

IUPAC (International Union of Pure and Applied Chemistry)/ Chemical name

4-amino-N-(5-methyl-1,2-oxazol-3-yl)benzenesulfonamide;5-[(3,4,5-trimethoxyphenyl)methyl]pyrimidine-2,4-diamine 

Intake routine/cycle

Daily dose

Take Sulfamethoxazole + Trimethoprim exactly as your doctor recommends. The dose may change based on your condition and how well you respond. Do not take more than prescribed without consulting your doctor. 

Missed Dose

If you forget to take your medicine, take the medication as soon as you remember. If it’s nearly time for your next dose, skip the missed one and continue with your regular schedule. Always consult the doctor before making any changes to your dosage. 

Overdose

Do not take more than the prescribed dose of Sulfamethoxazole 160 mg + Trimethoprim 800 mg (usually 1 tablet as advised by your doctor). Taking extra can increase side effects like nausea, vomiting, stomach upset, or rash. Contact your doctor immediately if severe symptoms occur. 

Storage

1. Store the medicine at room temperature 
2. Keep away from sunlight and moisture 
3. Keep out of reach of children 

Sulfamethoxazole + Trimethoprim Summary

Sulfamethoxazole + Trimethoprim is an oral antibiotic combination used to treat bacterial infections. It belongs to the sulfonamide and folate pathway inhibitor class and works by blocking bacteria from making folic acid, which is useful for the bacterial growth, without folic acid bacteria becomes weak, helping the body fight off infections. This medicine is used to treat infections in urinary tract, lungs like bronchitis or pneumonia, ear, stomach or gut, and certain infections in people with weakened immunity. It can be taken with or without food, and alcohol should be avoided.  

Common side effects include nausea, vomiting, stomach upset, diarrhea, loss of appetite, and mild rash, while rare serious effects may include severe allergic reactions, blood disorders, liver or kidney problems, and severe skin reactions. It should not be taken by people allergic to sulfamethoxazole and trimethoprim, with severe liver or kidney disease, blood disorders, or during pregnancy and breastfeeding without doctor approval. It should not be taken more than one tablet (160 mg + 800 mg); overuse can increase side effects.  

FAQ’s

What are the uses of Sulfamethoxazole + Trimethoprim? 

This combination antibiotic is used to treat bacterial infections such as urinary tract infections, respiratory infections like bronchitis or pneumonia, ear infections, stomach or gut infections, and certain infections in people with weakened immunity. 

What are the side effects of Sulfamethoxazole + Trimethoprim? 

Common side effects include nausea, vomiting, stomach upset, diarrhea, loss of appetite, and mild rash. Rare but serious side effects may include severe allergic reactions, blood problems, liver or kidney issues, and severe skin reactions. If serious symptoms occur, contact your doctor immediately.

What class of medicine does Sulfamethoxazole + Trimethoprim belong to?

Sulfamethoxazole + Trimethoprim belongs to the antibiotic class, specifically a combination of sulfonamide and folate pathway inhibitor, used to treat bacterial infections.  

What are the brand names of Sulfamethoxazole + Trimethoprim?

This combination is available under several brand names, including Bactrim, Septrim, Cotrim, and Co-Trimoxazole, depending on the country and manufacturer. At SayaCare we provide medicines with their original name i.e. generic drugs, at up to 80% lower than market prices, making quality healthcare more affordable. 

Reference 

1. Sulfamethoxazole / Trimethoprim Dosage Guide with Precautions [Internet]. Drugs.com. Available from 
2. Kemnic TR, Coleman M. Trimethoprim Sulfamethoxazole [Internet]. NIH.gov. StatPearls Publishing; 2022. Available from 
3. PubChem. Sulfamethoxazole- trimethoprim mixt. [Internet]. Nih.gov. PubChem; 2025 [cited 2025 Dec 19]. Available from 

Pranathi Chintaluri

Pranathi is a final year Pharm D student at Chalapathi Institute of Pharmaceutical Sciences. She loves learning and applying her knowledge in pharmacy and has a passion for writing, which allows her to express ideas clearly and creatively. She enjoys combining her technical skills with her love for writing and communication to make a meaningful impact. Currently she is working on a research paper about “Consanguineous marriages and its impact on children’s health” which will be published by the end of 2025.