DMARDs (Disease-Modifying Anti-Rheumatic Drugs)

🔍 When to Suspect

A patient on a DMARD presents with new signs of infection (e.g., sore throat, fever), bone marrow suppression (e.g., bruising), or liver/lung toxicity

From the full topic in The Ocean Library: DMARDs (Disease-Modifying Anti-Rheumatic Drugs)

🧭 When to suspect toxicity (and the shared-care role)

Disease-modifying anti-rheumatic drugs (DMARDs) are specialist-initiated immunomodulators used in autoimmune and inflammatory disease – rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, SLE and connective-tissue disease, vasculitis, juvenile idiopathic arthritis, psoriasis, and inflammatory bowel disease. They control the disease process rather than just symptoms, but every one of them carries a risk of bone-marrow suppression, hepatotoxicity, infection, and (for some) organ-specific toxicity, which is why structured monitoring is mandatory.

In primary care the GP almost always meets these drugs through a shared-care agreement: rheumatology (or dermatology/gastroenterology) initiates, stabilises and retains overall responsibility, then asks the GP to continue prescribing and to perform the agreed blood monitoring. The single golden rule of that contract is simple – no satisfactory, up-to-date monitoring means no prescription. Never issue a repeat if the bloods are overdue, missing, or abnormal.

The two core GP skills are therefore safe shared-care monitoring and recognising toxicity. Suspect an adverse effect whenever a patient on a DMARD presents with infection, signs of marrow suppression (unexplained bruising, bleeding, sore throat, mouth ulcers), liver toxicity (jaundice, nausea), or respiratory symptoms (new cough or breathlessness).

DMARD	Routine bloods (per local protocol)	Key toxicities & cautions
Methotrexate	FBC, U&E, LFT	Myelosuppression, hepatotoxicity, pneumonitis. Once weekly; co-prescribe folic acid; never with trimethoprim / co-trimoxazole.
Sulfasalazine	FBC, LFT	Myelosuppression (esp. first months), hepatitis, rash. Not significantly immunosuppressive.
Hydroxychloroquine	No routine bloods; annual eye review	Long-term retinopathy. Not significantly immunosuppressive.
Leflunomide	FBC, LFT, BP, weight	Hepatotoxicity, hypertension, diarrhoea/weight loss. Long half-life – needs cholestyramine washout.
Azathioprine	FBC, LFT; check TPMT before starting	Myelosuppression. Never full-dose with allopurinol (life-threatening toxicity).
Mycophenolate	FBC, LFT	Myelosuppression, GI upset. Strongly teratogenic (men and women).

Source: BSR 2025 csDMARD guideline · MHRA

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