IL-17 inhibitors raised candidiasis risk; TNF inhibitors carried most of the tuberculosis

Design

Nationwide prospective registry cohort with entropy balancing

Population

18,635 adults with psoriasis; 40,930 systemic treatment episodes; 118,018 person-years

Primary outcome

Tuberculosis, meningitis, candidiasis and other fungal infections

Effect

Candidiasis on IL-17 inhibitors IRR 2.67 (95% CI 1.33 to 5.36) vs apremilast to 4.65 (3.46 to 6.24) vs IL-12/23

A nationwide cohort from the British Association of Dermatologists Biologic and Immunomodulators Register (British Journal of Dermatology, 15 September 2026) followed 18,635 adults with psoriasis through 40,930 courses of systemic treatment, 118,018 person-years in all, from 2007 to 2024. Groups were balanced on measured characteristics before comparison.

Tuberculosis (22 cases, 0.19 per 1,000 person-years) and meningitis (29 cases, 0.25 per 1,000) were rare. Most of both occurred on TNF inhibitors, particularly adalimumab; meningitis was mainly viral and tuberculosis mainly pulmonary. Fungal infection was far commoner, 888 cases or 7.53 per 1,000 person-years, half of them candidiasis. IL-17 inhibitors carried a higher candidiasis risk than every other group, from 2.67 times that of apremilast to 4.65 times that of IL-12/23 inhibitors. Individual IL-17 inhibitors did not differ.

The tuberculosis figures come from a low-incidence country and will not transfer to India, where the background rate is far higher. The candidiasis signal is likely to travel. For a patient with recurrent oral or genital candidiasis, or one in whom it would be hard to manage, an IL-17 inhibitor may not be the best first choice.

• Warn patients starting an IL-17 inhibitor about oral and genital thrush and what to do about it.
• Ask about candidiasis at each review on IL-17 inhibitors; most cases are treatable without stopping.
• Consider an IL-23 or IL-12/23 inhibitor for patients with recurrent candidiasis.
• Consider non-TNF options where tuberculosis risk is high and other factors are equal.
• Do not assume switching between IL-17 inhibitors will reduce candidiasis; the risk was similar across the class.

Why it matters

It turns a known class effect into a comparative risk that can shape the choice of first biologic.

Don't overread it

The low tuberculosis rates come from the UK and should not be applied to Indian patients.

The statistics, in plain English

An incidence rate ratio of 4.65 means candidiasis occurred at almost five times the rate on IL-17 inhibitors as on IL-12/23 inhibitors. With only 22 tuberculosis cases in total, comparisons between drugs for TB are imprecise, which is why the paper describes rather than ranks them.

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