JAK Inhibitor (JAK1/JAK2 Inhibitor)

Baricitinib

Brand names: Olumiant

Baricitinib is an oral Janus kinase (JAK) inhibitor used in rheumatoid arthritis and other immune-mediated conditions such as atopic dermatitis and alopecia areata.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It inhibits JAK1 and JAK2, interrupting cytokine signalling pathways that drive inflammation in immune-mediated disease.

Prescribing in practice

The MHRA advises that JAK inhibitors carry risks of serious infection, venous thromboembolism, major cardiovascular events and malignancy, with cautious use particularly in older patients and those with risk factors.
Screen for and treat latent tuberculosis and chronic viral hepatitis before starting, and ensure vaccinations are up to date.
Avoid live vaccines during treatment.

Monitoring

Monitor full blood count, lipids, liver function and for signs of infection before and during treatment as set out in current prescribing references.

Counselling the patient

Report any signs of infection, chest pain, breathlessness or leg swelling promptly.
Avoid live vaccines and tell other clinicians you are taking an immunosuppressant.

Evidence & guidelines

MHRA safety reviews of JAK inhibitors inform their restricted use in patients with cardiovascular and malignancy risk factors.

Reference: NICE TA466; RA-BEAM trial; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways