Upadacitinib

JAK inhibitors
JAK inhibitors
Pregnancy: contraindicated
May harm the fetus: a pregnancy test is done before starting, and effective contraception is used during treatment and for at least 4 weeks after the last dose.

An oral JAK1 inhibitor for rheumatoid and psoriatic arthritis, atopic dermatitis, Crohn's disease, ulcerative colitis and spondyloarthritis.

Updated Nov 1, 2026

Quick facts

Group: JAK inhibitors
Target: Janus kinase 1 (JAK1)
Used for: Rheumatoid arthritis · Psoriatic arthritis
Key effects: Stuffy or runny nose · Nausea · Acne and folliculitis
Monitor: Latent tuberculosis · Cholesterol during treatment
ATC: L04AF03

No doses: the clinician sets them by the current guideline.

Mechanism of action

Janus kinase 1 (JAK1)Upadacitinib

The figure shows human JAK1 with abrocitinib, another JAK1 inhibitor that occupies the same ATP site; upadacitinib itself is not in this crystal.

Target in 3D: Janus kinase 1 (JAK1). PDB structure 6BBU (RCSB PDB, public domain). View the structure at RCSB PDB

Upadacitinib is a Janus kinase inhibitor that acts mainly on JAK1. Many inflammatory cytokines signal through JAK–STAT: with JAK1 blocked, STAT proteins are not switched on and immune cells make fewer inflammatory signals, which calms joint, skin and bowel inflammation.

Drug enters immune cells and blocks JAK1
Cytokine receptors cannot switch on STAT proteins
Fewer inflammatory genes are transcribed
Joint, skin and bowel inflammation settles

Indications

Rheumatoid arthritis Rheumatoid arthritis →
Psoriatic arthritis Psoriatic arthritis →
Atopic dermatitis Atopic dermatitis →
Ulcerative colitis Ulcerative colitis →
Crohn's disease Crohn disease →
Ankylosing spondylitis and non-radiographic axial spondyloarthritis Ankylosing spondylitis →
Polyarticular juvenile idiopathic arthritis Juvenile idiopathic arthritis →
Giant cell arteritis Giant cell arteritis →

Adverse effects

Common

Stuffy or runny nose
Nausea
Acne and folliculitis
Headache
Weight gain

Contraindications

Hypersensitivity to upadacitinib
Active serious infection, including active tuberculosis
Pregnancy (may harm the fetus)

Key interactions

Strong CYP3A4 inhibitors (such as ketoconazole): Higher JAK-inhibitor levels and more adverse effects.
Other strong immunosuppressants and biologics: Combination is generally not recommended: added infection risk.
Live vaccines: Avoided during treatment; vaccines, including herpes zoster vaccine, are given before starting.
Grapefruit and grapefruit juice: Avoided during treatment.

What is monitored

Latent tuberculosis, hepatitis B and C, and pregnancy test before starting
Cholesterol during treatment
Blood counts and other laboratory tests ordered by the team
Signs of infection, chest pain, stroke or blood clots

Administration and safety

Tablets are swallowed whole, not split, crushed or chewed.
Whole tablets or pieces seen in the stool are reported to the team.
Grapefruit is avoided while on treatment.
Vaccines, including herpes zoster vaccine, are brought up to date before starting.

Pregnancy and breastfeeding

May harm the fetus: a pregnancy test is done before starting, and effective contraception is used during treatment and for at least 4 weeks after the last dose.

Nursing care

Before starting, confirm tuberculosis, hepatitis and pregnancy tests and ask about smoking, heart disease, clots and cancer.
Teach to report fever, cough or painful skin, and to seek urgent care for chest pain, sudden breathlessness, leg swelling or stroke signs.
Teach to report sudden vision changes and severe abdominal pain with fever.
Remind about effective contraception and no breastfeeding during treatment and for a short time after the last dose.

Pharmacokinetics

Absorption: Oral, as an extended-release tablet or an oral solution
Metabolism: Strong CYP3A4 inhibitors raise its levels, as with most JAK inhibitors

Test yourself

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

Which Janus kinase does upadacitinib mainly block?

JAK1.

What four groups of risks are in the boxed warning for oral JAK inhibitors such as upadacitinib?

Serious infections, cancers (including lymphoma), major heart events and stroke, and blood clots.

Which food is avoided during upadacitinib treatment?

Grapefruit and grapefruit juice.

Add to my cards (3)

Connections

← Back to the class: 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: Upadacitinib: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); RCSB PDB - 6BBU: Crystal Structure of JAK1 in complex with compound 25 (RCSB Protein Data Bank, 2018); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).

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Representative model, for educational purposes only.