Educational draft · awaiting clinical reviewUse Rapid for revision, not patient-care decisions. Check current national and local guidance and the BNF or BNFC before acting.
2 min synopsisUK scopeSources checked 27 Aug 2026Clinical review pending
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Serious infection, thrombosis or cardiovascular event
Sepsis, disseminated zoster, tuberculosis, pulmonary embolism, deep-vein thrombosis, myocardial infarction, stroke or bowel perforation can occur during JAK inhibition, with greatest concern in older people, smokers and those with vascular, cancer or infection risk.
Action: Stop the targeted medicine, arrange emergency syndrome-specific assessment and treatment, and notify rheumatology; do not restart until infection or vascular evaluation is complete and the class-level risk-benefit decision has been reconsidered.
Synopsis
Use oral JAK inhibitors and other targeted synthetic DMARDs only after guideline-based risk stratification, with exact dosing, infection and laboratory screening, and active prevention of cardiovascular, thrombotic, malignant and reproductive harm.
JAK inhibitors are oral small molecules that block intracellular cytokine signalling; faster onset and oral convenience do not make them lower-risk than injectable biologics.
MHRA requires all JAK inhibitors for chronic inflammatory disorders to be used only when no suitable alternatives exist in people aged 65 or over, current or past long-term smokers, and those with cardiovascular or malignancy risk.
Use caution in anyone with venous-thromboembolism risk and use the lower authorised dose where the product recommends it for risk reduction.
Key red flags
Fever, hypotension, confusion, hypoxaemia, widespread vesicles or focal severe infection requires immediate JAK-inhibitor withholding and urgent antimicrobial assessment.
Herpes zoster
Pain, dysaesthesia and grouped vesicles can be subtle; ophthalmic distribution, dissemination, neurological features or immunocompromised systemic illness is urgent.
Investigation priorities
01
First-line vascular and cancer risk inventoryFirst stepFirst line
Determine whether MHRA requires use only after suitable alternatives and whether VTE risk is acceptable.
Management branches
First selection gateCompare JAK risk with suitable alternatives
A targeted synthetic DMARD is being considered after the disease-specific prior-treatment sequence.
Confirm active inflammatory disease and NICE eligibility, then document age, smoking, cardiovascular, malignancy, VTE, infection and reproductive risk.
In MHRA high-risk groups, use a JAK inhibitor only if no suitable alternative can meet the same clinical need and record why.
Apremilast routeTitrate and watch weight and mood
Psoriatic disease meets an apremilast pathway and a less immunosuppressive oral option is preferred.
Key medicines
TofacitinibGive 5 mg orally twice daily for adult rheumatoid or psoriatic arthritis; reduce to 5 mg once daily in specified moderate or severe renal impairment, moderate hepatic impairment or potent interaction settings under the product table.
BaricitinibGive 4 mg orally once daily for adult rheumatoid arthritis; use 2 mg once daily in adults aged 65 or over and when product-defined infection, VTE, MACE, malignancy or renal factors favour the lower authorised dose.
National guidance is shown before implementation-dependent detail. Typical adult dose examples remain subject to patient factors, contraindications and the live BNF or specialist protocol. Source check completed 27 Aug 2026; clinical approval remains outstanding.