[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [JAK inhibitors](https://durgical.com/en/pharmacology/classes/jak-inhibitors/) › Baricitinib

[Pharmacology](https://durgical.com/en/pharmacology/) · [JAK inhibitors](https://durgical.com/en/pharmacology/classes/jak-inhibitors/)

# Baricitinib

An oral JAK1/JAK2 inhibitor for rheumatoid arthritis after a TNF blocker, alopecia areata and severe COVID-19 in hospital.

Updated 2026-11-01

- Class: [JAK inhibitors](https://durgical.com/en/pharmacology/classes/jak-inhibitors/)
- Enzyme: Janus kinases JAK1 and JAK2
- ATC code: L04AF02

✂**Janus kinases JAK1 and JAK2**Baricitinib

ⓘ The figure shows the human JAK2 kinase domain with baricitinib in its ATP site.

**Target in 3D:** Janus kinases JAK1 and JAK2. PDB structure 6VN8 (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/6VN8) · Drag to rotate · pinch to zoom

## Mechanism of action

Baricitinib is a reversible ATP-competitive inhibitor of JAK1 and JAK2. It reduces signalling of cytokines such as IL-6 and the interferons, which lowers STAT activation, lymphocyte activity and inflammation; in severe COVID-19 it damps the excessive inflammatory response.

- Binds the ATP site of JAK1 and JAK2
- STATs are not phosphorylated
- Less cytokine-driven inflammation

## Pharmacokinetics

**Absorption**
Oral, once daily

**Elimination**
Kidney disease is taken into account before and during treatment

## Indications

- Rheumatoid arthritis after one or more TNF inhibitors [Rheumatoid arthritis →](https://durgical.com/en/conditions/rheumatoid-arthritis/)
- Alopecia areata [Alopecia areata →](https://durgical.com/en/conditions/alopecia-areata/)
- COVID-19 in hospitalised adults who need oxygen, ventilation or ECMO [COVID-19 →](https://durgical.com/en/conditions/covid-19/)

## Adverse effects

### Common

- Upper respiratory infections
- Nausea
- Raised cholesterol
- Herpes zoster

### Serious (rare, important)

- Serious infections, including tuberculosis, opportunistic infections and herpes zoster
- Major cardiovascular events (heart attack, stroke, cardiovascular death)
- Venous and arterial thrombosis, including pulmonary embolism
- Lymphoma, lung cancer and skin cancer
- Gastrointestinal perforation: abdominal pain with fever and change in bowel habit
- Anaemia and low white cell counts

## Contraindications

- Active serious infection, including active tuberculosis
- Hypersensitivity to baricitinib

## Key interactions

**Other immunosuppressants and biologic DMARDs**
Added immunosuppression and infection risk.

**Live vaccines**
Avoided during treatment.

## What is monitored

- Latent TB test before and during treatment
- Blood count, liver tests, kidney function and cholesterol
- Signs of thrombosis and new abdominal pain

## Administration and safety

- Oral tablet, with or without food, at about the same time each day.

## Nursing care

- Before starting, confirm the latent TB test, hepatitis screening, blood count and up-to-date vaccines.
- Ask about smoking, previous heart attack, stroke or blood clots.
- Teach the signs of a clot (painful swollen leg, sudden shortness of breath, chest pain) and of shingles (painful band-shaped rash).
- Live vaccines are avoided during treatment.
- Ask about kidney disease, ulcers or diverticulitis; breastfeeding is avoided during treatment and for a short time after.

## Pregnancy and breastfeeding

Human data are limited; the treating team weighs benefits and risks.

## Memory aid

BARIcitinib: a BARrier on JAK1 and JAK2 — joints, hair (alopecia) and COVID lungs.

## Test yourself

Think of the answer, then tap the question to see it.

## Which Janus kinases does baricitinib inhibit?

JAK1 and JAK2.

## Which hair-loss disease is an indication for baricitinib?

Alopecia areata.

## Which serious cardiovascular risks share a warning with baricitinib and tofacitinib?

Heart attack, stroke and blood clots in the legs, lungs or arteries.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/baricitinib/)

## Related drugs

- [Tofacitinib](https://durgical.com/en/pharmacology/tofacitinib/)
- [Ruxolitinib](https://durgical.com/en/pharmacology/ruxolitinib/)

## Related conditions

- [Rheumatoid arthritis](https://durgical.com/en/conditions/rheumatoid-arthritis/)
- [Alopecia areata](https://durgical.com/en/conditions/alopecia-areata/)
- [COVID-19](https://durgical.com/en/conditions/covid-19/)

[← Back to the class: JAK inhibitors](https://durgical.com/en/pharmacology/classes/jak-inhibitors/)

Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: [Baricitinib: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a618033.html) (MedlinePlus (U.S. National Library of Medicine), 2022); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 39 (McGraw Hill, 2023); [Altered Immunocompetence | Vaccines & Immunizations | CDC](https://www.cdc.gov/vaccines/hcp/acip-recs/general-recs/immunocompetence.html) (Centers for Disease Control and Prevention (CDC), 2024); [ATCDDD - ATC/DDD Index](https://atcddd.fhi.no/atc_ddd_index/?code=L04AF02) (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

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Source: https://durgical.com/en/pharmacology/baricitinib/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/baricitinib/