Adalimumab

Adalimumab is prescribed to treat:

• Rheumatoid arthritis, psoriasis, crohn's disease, and other inflammatory conditions • Various related conditions in the immunology category • Associated symptoms and complications

It is an important medication that helps manage these conditions effectively.

Adalimumab (Humira) is a tumour necrosis factor inhibitor used for rheumatoid arthritis, psoriatic arthritis, psoriasis, ankylosing spondylitis, Crohn's disease, and ulcerative colitis. It was among the first biologics to transform outcomes in inflammatory disease, and the treatment landscape it created still defines how these conditions are managed.

Mechanism of Action

Adalimumab is a fully human monoclonal antibody that binds tumour necrosis factor alpha, a pro-inflammatory cytokine central to the inflammatory cascade in these diseases. It neutralises both soluble and membrane-bound TNF, preventing it from engaging its receptors, and it also induces apoptosis in TNF-expressing cells.

TNF sits high in the inflammatory hierarchy, driving production of downstream cytokines, adhesion molecules, and matrix metalloproteinases. Blocking it therefore interrupts many effects at once, which is why TNF inhibitors act broadly across quite different diseases that share this pathway.

Being fully human rather than chimeric reduces immunogenicity relative to infliximab, though anti-drug antibodies still form and are a leading cause of loss of response over time. Concurrent methotrexate reduces antibody formation, which is the main reason biologics are usually added to methotrexate rather than replacing it.

The same mechanism that controls inflammation impairs the immune response to intracellular pathogens. TNF is essential to forming and maintaining granulomas, which is why tuberculosis reactivation is the signature risk of this class — the granuloma that had contained latent infection breaks down.

Screening Before Starting

Screening is mandatory before the first dose, not optional, and it is the single most important safety step.

Latent tuberculosis testing — an interferon-gamma release assay or tuberculin skin test — plus a chest radiograph is required. A positive result means treating the latent infection before or alongside starting the biologic. Reactivation on a TNF inhibitor is frequently extrapulmonary and disseminated, and presents atypically, so it is easy to miss.

Hepatitis B screening is also required, since TNF inhibition can reactivate hepatitis B, sometimes fulminantly. Hepatitis C status is checked. Vaccinations should be brought up to date beforehand, because live vaccines are contraindicated once treatment begins and responses to inactivated vaccines are better before immunosuppression.

These steps are occasionally compressed when a patient is in a flare and treatment feels urgent. They should not be. Our immunology and musculoskeletal teams manage this screening, and the American College of Rheumatology publishes patient-level guidance.

Clinical Use

Adalimumab is used when conventional therapy has failed — in rheumatoid arthritis, that generally means inadequate response to methotrexate. It is given by subcutaneous injection, usually every other week, and patients self-administer at home after training.

Onset is faster than with conventional DMARDs, often within weeks, though full benefit takes longer. Loss of response after initial success is common and usually reflects anti-drug antibodies; options then include increasing frequency, adding or optimising methotrexate, or switching — either to another TNF inhibitor, since response to one does not predict response to another, or to a different mechanism such as an IL-17 inhibitor, IL-23 inhibitor, or JAK inhibitor.

Biosimilars are now available and are substantially cheaper. They are highly similar with no clinically meaningful differences, and switching is generally appropriate, though patients often want the reasoning explained rather than presented as a substitution. Cost and access remain significant practical barriers, and coverage interruptions cause loss of disease control that is not always recoverable.

Monitoring and Follow-Up

Periodic complete blood count, liver enzymes, and kidney function are checked, in part because of concurrent methotrexate. Tuberculosis screening is repeated at intervals depending on ongoing exposure risk.

Infection surveillance is the main clinical monitoring. Serious bacterial, fungal, and opportunistic infections are increased, and — critically — the usual inflammatory signs are blunted. A patient on a TNF inhibitor can have a significant infection with a modest fever and unimpressive examination findings, so the threshold for investigating should be lower than it would otherwise be.

Malignancy risk carries a boxed warning, principally lymphoma, with hepatosplenic T-cell lymphoma reported rarely in young patients with inflammatory bowel disease on combined immunosuppression. Absolute risk is low and much of the excess in inflammatory arthritis is attributable to the disease itself rather than the drug, but skin surveillance is warranted since non-melanoma skin cancer is increased — relevant in this climate.

The drug should be held during active serious infection and around major surgery. Demyelinating disease and new or worsening heart failure are recognised concerns, and TNF inhibitors are avoided in moderate to severe heart failure. The MedlinePlus adalimumab entry covers prescribing detail.

Special Populations

In older adults, infection and malignancy risks are higher and warrant a more explicit discussion of the balance, though effective disease control also reduces the harms of chronic inflammation and long-term corticosteroids.

In pregnancy, TNF inhibitors are increasingly used where disease activity warrants, since uncontrolled inflammatory disease carries its own fetal risk. Adalimumab crosses the placenta in the third trimester, so infants exposed late in pregnancy should not receive live vaccines for a defined period — a point that must be communicated to the paediatrician, and is often missed. Live vaccines are contraindicated in the patient throughout treatment. Hepatitis B carriers require antiviral prophylaxis.

When to Contact Your Doctor

Report any sign of infection promptly — fever, persistent cough, night sweats, unexplained weight loss, or feeling generally unwell — remembering that the usual signs may be muted. Persistent cough with weight loss and night sweats specifically raises tuberculosis and needs urgent assessment.

Report new or changing skin lesions given the skin cancer risk. Report new numbness, tingling, weakness, or visual disturbance, which can indicate demyelinating disease. Increasing breathlessness or ankle swelling may signal heart failure. Report injection site reactions that are severe or spreading.

Hold your dose and contact us during any significant infection or before planned surgery rather than deciding alone.

To review your screening, discuss loss of response, or address infection risk, contact us or schedule a visit.