Key Facts
- Drug Class
- Sulfonamide-diaminopyrimidine combination antibiotic
- Prescription
- Required
- NAFDAC Status
- NAFDAC Registered
- Forms
- Tablet, Suspension, Injection
- Price Range
- ₦100 - ₦3,000
- WHO Essential
- Yes
What is Co-trimoxazole (Sulfamethoxazole/Trimethoprim)?
Co-trimoxazole, universally known in Nigeria as Septrin, is arguably the single most self-medicated drug in the country. Walk into any patent medicine store from Mushin to Maiduguri, from Aba to Abeokuta, and you will find Septrin prominently displayed. It is a combination antibiotic containing two active ingredients — sulfamethoxazole and trimethoprim — that work together to block two consecutive steps in the bacterial production of folic acid, a nutrient essential for bacterial growth and survival. By attacking bacteria at two different points in the same metabolic pathway, co-trimoxazole achieves a synergistic bactericidal effect that is more potent than either component alone.
In Nigeria, Septrin has achieved a cultural status that goes far beyond its clinical indications. Many Nigerians regard it as a cure-all, self-prescribing it for everything from headaches to malaria to sexually transmitted infections — most of which it is not effective against. This indiscriminate use has contributed significantly to the growing problem of antibiotic resistance in Nigeria. The original Septrin brand by GlaxoSmithKline (GSK) set the standard, but numerous locally manufactured generics including Emtrim (Emzor) and other brands are widely available at lower prices. All legitimate co-trimoxazole products must carry a NAFDAC registration number.
Despite the problem of misuse, co-trimoxazole remains a genuinely important antibiotic with specific, valuable roles. It is a WHO Essential Medicine and plays a critical role in the prevention of opportunistic infections in HIV-positive patients — Nigeria has one of the largest HIV-positive populations in the world, and co-trimoxazole preventive therapy (CPT) is a cornerstone of HIV care. It is also effective for urinary tract infections, certain respiratory infections, and some types of diarrhoea when used appropriately. The key message for Nigerians is clear: Septrin is a real antibiotic with real side effects and real resistance consequences — it should only be taken when properly indicated, not as a first response to every illness.
What is Co-trimoxazole (Sulfamethoxazole/Trimethoprim) used for?
In Nigeria, Co-trimoxazole (Sulfamethoxazole/Trimethoprim) is commonly used for:
- Urinary tract infections (UTIs) — one of the most appropriate uses of co-trimoxazole, particularly for uncomplicated lower UTIs in women
- Acute otitis media (ear infections) in children — a common reason for co-trimoxazole prescription in Nigerian paediatric clinics
- Prophylaxis against opportunistic infections in HIV-positive patients (co-trimoxazole preventive therapy or CPT) — a lifesaving intervention in Nigeria's HIV programme
- Pneumocystis jirovecii pneumonia (PCP) prevention and treatment — an important opportunistic infection in people with advanced HIV/AIDS
- Acute exacerbations of chronic bronchitis in adults
- Traveller's diarrhoea caused by susceptible bacteria
- Toxoplasmosis prophylaxis and treatment in immunocompromised patients
- Nocardia infections and certain other specific bacterial infections as directed by a doctor
Dosage
IMPORTANT
Always follow your doctor's or pharmacist's instructions. The information below is for general reference only.
Adults
The standard adult dose is 960mg (two 480mg tablets, or one double-strength 960mg tablet) taken twice daily for 5 to 7 days for most infections. For urinary tract infections, 960mg twice daily for 3 to 5 days is often sufficient. For HIV prophylaxis (CPT), the standard dose is 960mg once daily, taken every day indefinitely or until immune recovery on antiretroviral therapy as determined by the doctor. Take with a full glass of water and ensure adequate fluid intake throughout the course to prevent crystal formation in the kidneys.
Children
Dosing in children is based on the trimethoprim component: 4mg TMP per kilogram per dose, given twice daily. For children aged 6 months to 5 years: 240mg (5ml of suspension or half a 480mg tablet) twice daily. For children aged 6 to 12 years: 480mg (10ml suspension or one 480mg tablet) twice daily. Co-trimoxazole suspension (240mg/5ml) is the preferred formulation for young children. Always use the measuring device provided. Co-trimoxazole should NOT be given to infants under 6 weeks of age.
Elderly
Elderly patients may require dose adjustment due to reduced kidney function. A lower dose or longer interval between doses may be necessary. Elderly patients are also at increased risk of serious side effects including severe skin reactions and blood disorders. Regular monitoring of blood counts and kidney function is advisable.
Drink plenty of water while taking co-trimoxazole — at least 6 to 8 glasses per day — to help prevent the drug crystallising in the kidneys. Do not take co-trimoxazole if you are allergic to sulfonamides or trimethoprim. Complete the full course of treatment even if you feel better after a day or two. For HIV prophylaxis, do not stop taking the daily dose without your doctor's instruction. Avoid prolonged sun exposure while on co-trimoxazole as it can cause photosensitivity.
Side Effects
Common side effects
- •Nausea and vomiting — the most frequently reported side effect
- •Diarrhoea and abdominal discomfort
- •Loss of appetite
- •Skin rash — may be mild but can progress to a serious reaction; stop the drug if a rash appears
- •Headache
Serious side effects — seek medical help immediately
- Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) — life-threatening skin reactions causing widespread blistering and peeling of the skin. More common in patients with HIV. If you develop a rash with blistering, mouth sores, or fever, stop co-trimoxazole immediately and seek emergency care
- Blood disorders — including anaemia, low white blood cell count (agranulocytosis), and low platelet count (thrombocytopenia), which can cause unusual bleeding, bruising, or increased susceptibility to infections
- Severe allergic reaction (anaphylaxis) — difficulty breathing, swelling of the face or throat, and widespread rash
- Liver damage (hepatitis) — yellowing of the skin or eyes, dark urine, severe fatigue
- Kidney damage — crystal formation in the kidneys (crystalluria), particularly when fluid intake is inadequate
- Hyperkalaemia (dangerously high potassium levels) — particularly in elderly patients or those with kidney problems
When to see a doctor
Stop taking co-trimoxazole immediately and seek emergency medical attention if you develop a skin rash — even a mild one — as it can rapidly progress to a life-threatening reaction. Seek urgent care if you develop mouth sores, blistering skin, fever with rash, yellowing of the skin or eyes, unusual bruising or bleeding, sore throat with fever, or significantly reduced urine output. In Nigeria, where many people self-medicate with Septrin, it is particularly important to be aware of these warning signs. If you are HIV-positive and develop a rash on co-trimoxazole prophylaxis, do not simply continue — see your doctor, as desensitisation protocols may be needed.
Warnings & Precautions
Do not take Co-trimoxazole (Sulfamethoxazole/Trimethoprim) if you have:
- Known allergy to sulfonamide drugs or trimethoprim — this is an absolute contraindication. Many Nigerians with sulfa allergies are unaware of the risk
- Severe liver disease or jaundice
- Severe kidney impairment (creatinine clearance below 15ml/min) without dialysis support
- Infants under 6 weeks of age
- Megaloblastic anaemia due to folate deficiency — co-trimoxazole further depletes folate
- Porphyria
- Pregnancy in the first trimester and near term (see pregnancy section)
Drug interactions
- •Warfarin — co-trimoxazole significantly increases the anticoagulant effect of warfarin, risking dangerous bleeding; INR must be closely monitored
- •Methotrexate — co-trimoxazole increases methotrexate toxicity by displacing it from protein binding and reducing its clearance; this combination should be avoided
- •Phenytoin — co-trimoxazole increases phenytoin blood levels, risking toxicity
- •ACE inhibitors and ARBs (lisinopril, losartan) — combined with co-trimoxazole, the risk of dangerously high potassium levels increases significantly, especially in elderly patients
- •Oral hypoglycaemics (glibenclamide, glipizide) — co-trimoxazole can increase their blood sugar-lowering effect, causing hypoglycaemia
- •Dapsone — increased risk of both drugs' side effects
- •Lamivudine — co-trimoxazole can increase lamivudine levels; relevant for HIV patients on both drugs in Nigeria
Pregnancy & Breastfeeding
Co-trimoxazole should be avoided during pregnancy, particularly in the first trimester (risk of neural tube defects due to folate antagonism) and near term (risk of neonatal jaundice and kernicterus). However, for HIV-positive pregnant women already on co-trimoxazole preventive therapy, WHO guidelines recommend continuing CPT throughout pregnancy because the benefits of preventing opportunistic infections outweigh the risks — this should be done under close medical supervision with concurrent folic acid supplementation. Co-trimoxazole passes into breast milk in small amounts but is generally considered compatible with breastfeeding at standard prophylactic doses. The drug should not be given to breastfeeding mothers of premature infants or babies with jaundice or G6PD deficiency.
Brands of Co-trimoxazole (Sulfamethoxazole/Trimethoprim) in Nigeria
4 brands available in Nigeria.
| Brand Name | Manufacturer | Strength | Form | NAFDAC Reg. No. |
|---|---|---|---|---|
| Septrin | GlaxoSmithKline (GSK) | 480mg, 960mg, 240mg/5ml | Tablet | 04-0150 |
| Bactrim | Roche | 480mg, 960mg | Tablet | |
| Emtrim | Emzor | 480mg, 960mg, 240mg/5ml | Tablet | 04-0267 |
| Lazar Cotrimoxazole | Tuyil Pharmaceutical | 480mg, 960mg | Tablet |
How to Verify Your Co-trimoxazole (Sulfamethoxazole/Trimethoprim) is Genuine
- 1Check for a valid NAFDAC registration number on the packaging — given the widespread availability of co-trimoxazole in Nigeria, the risk of counterfeit products is significant
- 2Use the NAFDAC Mobile Authentication Service (MAS): scratch the verification panel and send the code to 38353, or use the NAFDAC Green Book portal at greenbook.nafdac.gov.ng
- 3Purchase from licensed pharmacies and registered patent medicine stores — avoid buying Septrin from roadside vendors, bus stops, or unregistered market stalls
- 4Check the packaging for clear manufacturer details, batch number, manufacturing date, and expiry date. For GSK Septrin, verify the distinctive blister pack design and print quality
- 5Genuine co-trimoxazole tablets should be smooth, uniformly coloured, and of consistent size. Reject any tablets that appear crumbly, discoloured, or have an unusual smell
- 6Be cautious of unusually cheap Septrin — if the price is significantly below ₦100 per strip for adult-strength tablets, the product may be substandard or counterfeit
Co-trimoxazole (Sulfamethoxazole/Trimethoprim) Price in Nigeria
Co-trimoxazole (Sulfamethoxazole/Trimethoprim) prices in Nigeria typically range from ₦100 to ₦3,000 per pack, depending on the brand, strength, and where you buy it.
₦100 – ₦3,000
per pack
Prices vary by location and vendor. Last updated: 2026-02-01
Where to Buy
Purchase Co-trimoxazole (Sulfamethoxazole/Trimethoprim) only from licensed pharmacies and verified distributors. Avoid buying medicines from unverified sources, roadside vendors, or unregistered market stalls.
Frequently Asked Questions
Sources
- •NAFDAC Greenbook — National Agency for Food and Drug Administration and Control registered products database
- •WHO Model List of Essential Medicines (23rd List, 2023)
- •British National Formulary (BNF)
- •Nigerian Standard Treatment Guidelines