What are IL-17 Inhibitors and how do they work?
IL-17 inhibitors are biologic drugs that block interleukin-17, a key protein that fuels inflammation in autoimmune diseases. These medications belong to a class of medicines called biologics, which are designed to target specific components of the immune system to reduce harmful inflammation. By blocking IL-17, these drugs help control the overactive immune response that causes symptoms in various autoimmune conditions.
What Conditions Do They Treat?
IL-17 inhibitors have proven effective for several autoimmune conditions, particularly those affecting the skin and joints:
- Moderate to severe plaque psoriasis - The most common indication, where these drugs help clear skin lesions
- Psoriatic arthritis - Reducing joint pain and swelling in patients who also have psoriasis
- Ankylosing spondylitis - A type of arthritis affecting the spine
- Non-radiographic axial spondyloarthritis - Early-stage spinal arthritis before structural damage appears
It's important to note that IL-17 inhibitors are not typically used for inflammatory bowel disease due to paradoxical effects that can actually worsen intestinal inflammation.
How IL-17 Inhibitors Work
IL-17 inhibitors work by targeting the inflammatory pathway at its source. These drugs target either IL-17A or the IL-17 receptor to block the inflammatory response. IL-17 is a pro-inflammatory cytokine that plays a crucial role in immune responses, but when overproduced, it contributes to chronic inflammation and tissue damage.
The medications help reduce redness, scaling, joint pain, and swelling by preventing IL-17 from binding to its receptors and triggering the inflammatory cascade. Patients typically begin seeing improvements within weeks, though full benefit may take longer to achieve.
FDA-Approved IL-17 Inhibitors
Currently, there are four main IL-17 inhibitors approved by the FDA:
- Cosentyx (secukinumab) - The first FDA-approved IL-17A antagonist, approved in 2015 for moderate-to-severe plaque psoriasis. It is additionally approved for psoriatic arthritis, ankylosing spondylitis, non-radiographic axial spondyloarthritis, enthesitis-related arthritis, and hidradenitis suppurativa.
- Taltz (ixekizumab) - Another IL-17A inhibitor used for similar conditions.
- Siliq (brodalumab) - An IL-17 receptor antagonist approved for moderate to severe plaque psoriasis.
- Bimzelx (bimekizumab) - The newest in class, this dual IL-17A/F inhibitor was recently approved and is the first to target both IL-17A and IL-17F. It is currently approved for plaque psoriasis, psoriatic arthritis, ankylosing spondylitis, non-radiographic axial spondyloarthritis, and hidradenitis suppurativa.
How IL-17 Inhibitors are Given
All IL-17 inhibitors are injected under the skin, either by prefilled syringe or auto-injector devices. This subcutaneous administration allows patients to self-inject at home after proper training. Dosing varies but usually involves injections every 2–4 weeks after initial loading doses. The loading phase typically involves more frequent injections initially to build up therapeutic levels in the body.
Related questions
- What are Monoclonal Antibodies and how do they work?
- How does Taltz compare to Cosentyx for psoriatic arthritis?
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Are IL-17 Inhibitors Safe?
IL-17 inhibitors are generally considered safe and well-tolerated, and have significantly improved treatment outcomes for conditions like psoriasis and psoriatic arthritis. However, like all medications, they do come with potential risks and side effects.
Common side effects include:
- Cold-like symptoms
- Diarrhea
- Injection site reactions
Rare but serious risks include:
- Increased risk of infections, especially respiratory tract infections and candidiasis (yeast infections)
- Brodalumab carries a suicide risk warning, which led to its restricted use and requires special monitoring
- Angioedema
- Anaphylaxis
- Inflammatory bowel disease (IBD)
While the incidence of new-onset IBD is low, caution is advised for patients with a history of IBD, as some studies suggest a potential for exacerbation or new onset in a small number of cases. The increased infection risk occurs because these drugs suppress part of the immune system that normally fights off certain types of infections.
IL-17 vs IL-23 Inhibitors
Both IL-17 and IL-23 inhibitors are effective treatments, but they work differently.
IL-17 inhibitors
- Act more directly on inflammation
- Often provide faster skin response
- Target the end-product of the inflammatory pathway
IL-23 inhibitors
- May offer longer-lasting remission with less frequent dosing
- Work upstream in the inflammatory cascade
- Target the cytokine that promotes IL-17 production
The choice between these treatments depends on your specific condition, symptoms, and response to other drugs. Some patients may respond better to one class over the other, and treatment selection should be individualized.
Bottom Line
IL-17 inhibitors are powerful tools for treating autoimmune skin and joint conditions. They represent a significant advancement in precision medicine, targeting specific inflammatory pathways rather than broadly suppressing the immune system. However, they're not interchangeable with other biologics, so treatment should be tailored to your specific needs.
These medications have transformed treatment outcomes for many patients with moderate to severe psoriasis and related conditions, offering the possibility of clear or nearly clear skin and significant improvement in quality of life. As with any treatment, the decision to use IL-17 inhibitors should involve careful discussion with your healthcare provider about the potential benefits and risks based on your individual medical situation.
References
- Batta, S., et. al. 2023. IL-17 and -23 Inhibitors for the Treatment of Psoriasis. EMJ Allergy Immunol. https://www.emjreviews.com/en-us/amj/allergy-immunology/article/il-17-and-23-inhibitors-for-the-treatment-of-psoriasis/
- Cosentyx [package insert]. Updated 2025. Novartis Pharmaceutical Corporation. Accessed on July 28, 2025 at https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=77c4b13e-7df3-42d4-81db-3d0cddb7f67a
- Demirel Öğüt, N., Ayanoğlu, M. A., Koç Yıldırım, S., Erbağcı, E., Ünal, S., & Gökyayla, E. (2025). Are IL-17 inhibitors superior to IL-23 inhibitors in reducing systemic inflammation in moderate-to-severe plaque psoriasis? A retrospective cohort study. Archives of dermatological research, 317(1), 232. https://doi.org/10.1007/s00403-024-03768-6
- Eshwar, V., et. al. 2022. A Review of the Safety of Interleukin-17A Inhibitor Secukinumab. Pharmaceuticals (Basel, Switzerland), 15(11), 1365. https://doi.org/10.3390/ph15111365
- Fauny, M., et. al. 2020. Paradoxical gastrointestinal effects of interleukin-17 blockers. Annals of the Rheumatic Diseases 2020;79:1132-1138. https://doi.org/10.1136/annrheumdis-2020-217927
- Kearns, D. G., Uppal, S., Chat, V. S., & Wu, J. J. 2021. Comparison of Guidelines for the Use of Interleukin-17 Inhibitors for Psoriasis in the United States, Britain, and Europe: A Critical Appraisal and Comprehensive Review. The Journal of clinical and aesthetic dermatology, 14(6), 55–59. PMCID: PMC8594534 PMID: 34804357
- Taltz [package insert]. Updated 2024. Eli Lilly and Company. Accessed on July 28, 2025 at https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ac96658a-d7dc-4c7c-8928-2adcdf4318b2
- Țiburcă, L., et. al. 2022. The Treatment with Interleukin 17 Inhibitors and Immune-Mediated Inflammatory Diseases. Current issues in molecular biology, 44(5), 1851–1866. https://doi.org/10.3390/cimb44050127
- Wang, J., Wang, C., Liu, L., Hong, S., Ru, Y., Sun, X., Chen, J., Zhang, M., Lin, N., Li, B., & Li, X. 2023. Adverse events associated with anti-IL-17 agents for psoriasis and psoriatic arthritis: a systematic scoping review. Frontiers in immunology, 14, 993057. https://doi.org/10.3389/fimmu.2023.993057
- Zenobia, C., & Hajishengallis, G. 2015. Basic biology and role of interleukin-17 in immunity and inflammation. Periodontology 2000, 69(1), 142–159. https://doi.org/10.1111/prd.12083
Read next
Cosentyx vs Humira: How do they compare?
Both Cosentyx and Humira are available as subcutaneous injections (which means given under the skin) and may be used to treat certain inflammatory conditions such as plaque psoriasis, psoriatic arthritis, hidradenitis suppurativa, and ankylosing spondylitis. Cosentyx is also available as an IV injection that can be administered by a healthcare provider. After an initial loading dose, Humira is given every two weeks and Cosentyx every four weeks. Continue reading
Does Cosentyx cause weight gain or loss?
Although weight gain or weight loss are not listed as side effects in the manufacturer's product information for Cosentyx, anecdotally several people have reported weight gain, some significant, during Cosentyx treatment. But most people who gained weight decided to continue with Cosentyx treatment because it had effectively cleared their psoriasis or psoriatic arthritis. Weight loss has been noted as a rare side effect of Cosentyx in post-marketing reports. Continue reading
What happens if Cosentyx is not refrigerated?
Cosentyx is a human monoclonal antibody, which is a man-made protein that may degrade (breakdown) if it is not refrigerated or if it has been exposed to heat, sunlight, or extreme cold. Even shaking Cosentyx may cause degradation. If Cosentyx has been stored in a way that has caused it to break down (degrade), then it may not work as well as it should. It is very important that you store your Cosentyx pen or prefilled syringe correctly in the refrigerator at 2ºC to 8ºC (36ºF to 46ºF) until you need to use it. Continue reading
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