Co-trimoxazole

General Information

Formulary antimicrobial: Use in accordance with Trust guidelines

AWaRe antibiotic classification: 'Access'. Use as per guidelines.

480 mg of co-trimoxazole consists of sulfamethoxazole 400 mg and trimethoprim 80 mg (ratio 5:1)
Doses throughout Trust adult antimicrobial guidelines are expressed as the total quantity of trimethoprim and sulfamethoxazole.

See Trust Safety Message for Prescription of co-trimoxazole for action points when prescribing co-trimoxazole.

For all information regarding interactions, contraception, pregnancy and breastfeeding and additional information, see BNF and Summary of Product Characteristics (SPC).

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	Oral co-trimoxazole dose	Intravenous co-trimoxazole dose
Standard dose	960mg BD
*Stenotrophomonas maltophilia* (or other organisms on advice of Micro/ID only)	960mg TDS
Pneumocystis jirovecii Pneumonia (PJP - formerly PCP)	See Pneumocystis jirovecii pneumonia (PJP) For dosing in renal impairment see below

Non-PCP indications:

There is no consensus on dosing in obesity. If body weight is over 120kg consider increasing to 960mg tds, particularly in patients with severe infections, considering patient’s renal function.

PCP:

Use adjusted bodyweight (AdjBW) if obese (BMI 30 or more).

Renal impairment

For all indications, including PCP

eGFR (mL/min/1.73m²)	Oral	Intravenous
More than 30	No adjustment
15-30	Half normal dose
Less than 15	Discuss with Micro/ID/pharmacy. Ideally, haemodialysis facilities should be available

Hepatic impairment
Avoid in severe hepatic impairment

Monitor:

U+Es daily. Risk of Acute kidney injury / hyperkalaemia. Risk factors are:
- age over 65 years old
- Chronic Kidney Disease
- current AKI
- current hyperkalaemia and/or hyponatraemia
- concurrent use of ACEi, ARBs or potassium-sparing diuretics (temporary dose adjustment or cessation of these drugs may be warranted, depending on indications)
Monitor FBC regularly. Risk of Myelosuppression, agranulocytosis, aplastic anaemia, other blood dyscrasias.
Monitor LFTs regularly.

Aspen. Co-Trimoxazole 80 mg/400 mg Tablets summary of product characteristics: Electronic Medicines Compendium [Internet]. Last revision of the text: February 2024.Accessed February 2025. Available from: https://www.medicines.org.uk/emc/product/6999/smpc
Aspen. Co-Trimoxazole 16 mg/ 80mg per ml for Infusion summary of product characteristics: Electronic Medicines Compendium [Internet]. Last revision of the text: February 2024. Accessed February 2025. Available from: https://www.medicines.org.uk/emc/product/4699/smpc
Joint Formulary Committee. British National Formulary (BNF). Accessed February 2025. Available from: https://www.medicinescomplete.com
The Renal Drug Database. Co-trimoxazole [Internet]. Last updated 29/10/24. Accessed February 2025. Available from: https://www.renaldrugdatabase.com/s/article/CO-TRIMOXAZOLE-TRIMETHOPRIM-SULFAMETHOXAZOLE
Boucher H. Trimethoprim-sulfamethoxazole - Sanford Web Guide [Internet]. Last updated 3/2/2025. Accessed 4/2/2025 Available from: https://web.sanfordguide.com/en/drug-information/antibacterial-agents/trimethoprim-sulfonamides/trimethoprim-sulfamethoxazole
Auwaerter PG. Trimethoprim-sulfamethoxazole – John Hopkins ABX guide [Internet]. 2023 [Accessed 4/6/24]. Available from: https://www.hopkinsguides.com/hopkins/view/Johns_Hopkins_ABX_Guide/540565/all/Trimethoprim_+_Sulfamethoxazole#11
UK Clinical Pharmacy Association. Drug dosing in extremes of body weight in critically ill patients, 1st edition [Internet]. 2013. Accessed February 2025. Available from: https://ukclinicalpharmacy.org/wp-content/uploads/2023/06/Drug-dosing-extreme-body-weight-2013-1Ed.pdf.
Meng L, Mui E, Ha DR, Stave C, Deresinski SC, Holubar M. Comprehensive guidance for antibiotic dosing in obese adults: 2022 update. Pharmacotherapy. 2023; 43(3):177-259.

Last reviewed: 03 Feb 2025

Next review date: 01 Feb 2028

Author(s): AMST.

General Information

Dosing

Obesity

Renal and hepatic impairment

Monitoring

References

Editorial Information