Can biologics used in RA also treat PsA? 

Many biologic therapies used in the treatment of Rheumatoid Arthritis (RA) are also highly effective and licensed for use in Psoriatic Arthritis (PsA). This is because both conditions are driven by similar overactive immune responses that involve the release of inflammatory proteins called cytokines. While the two diseases have distinct clinical features, they share several “target” pathways within the immune system. In the UK, the choice of biologic is guided by clinical evidence and specific NICE (National Institute for Health and Care Excellence) technology appraisals to ensure the most effective treatment for each condition. 

What We’ll Discuss in This Article 

• Shared biological pathways between Rheumatoid and Psoriatic Arthritis 

• Common classes of biologics licensed for both conditions 

• Biologics that are specific to Psoriatic Arthritis (Skin and Joint) 

• How UK clinicians decide which biologic to prescribe 

• The role of TNF inhibitors in treating systemic inflammation 

• Managing dual symptoms when both skin and joints are affected 

Many biologics used in RA can also treat PsA, particularly a class of drugs known as TNF inhibitors, which block a protein that causes inflammation in both the joints and the skin.³ While there is significant overlap in the treatments available, some newer biologics are specifically designed to target pathways that are unique to the psoriasis aspect of PsA, such as the IL-17 or IL-23 pathways. The NHS notes that biological treatments are usually only used if other DMARDs, such as methotrexate, have not worked or are not suitable for your specific type of arthritis. 

Shared Targets: TNF Inhibitors 

The most well-known class of biologics used for both RA and PsA is the TNF-alpha inhibitors. TNF (Tumour Necrosis Factor) is a cell-signalling protein involved in systemic inflammation. In both conditions, the body produces too much TNF, leading to joint swelling, pain, and damage. 

Because TNF is a central player in the inflammatory process for both diseases, drugs in this class are often the first biologic choice in the UK. Common TNF inhibitors licensed for both RA and PsA include: 

• Adalimumab 

• Etanercept 

• Infliximab 

• Certolizumab pegol 

• Golimumab 

These medications are highly effective at reducing joint inflammation and, in the case of PsA, can also lead to significant clearance of skin psoriasis. 

Differences in Biologic Targets 

While there is overlap, the immune systems in RA and PsA do not function identically. Some biologics that work exceptionally well for RA are less effective for PsA, and vice versa. For example, RA is often driven by B-cells or the IL-6 pathway, whereas PsA has a strong link to the IL-17 and IL-23 pathways, which are also heavily involved in skin psoriasis. 

For this reason, a patient with PsA might be prescribed an IL-17 inhibitor (such as Secukinumab) or an IL-23 inhibitor (such as Ustekinumab), which are not typically used for RA. Conversely, a drug like Rituximab, which targets B-cells in RA, is rarely used for PsA. NICE provides specific guidance on which biologics are recommended for each condition based on their effectiveness in clinical trials. 

Comparison of Biologic Licensing in the UK 

The following table outlines the common biologics and whether they are typically used for RA, PsA, or both. 

Biologic Class	Example Drug	Licensed for RA?	Licensed for PsA?
TNF Inhibitors	Adalimumab / Etanercept	Yes	Yes
IL-17 Inhibitors	Secukinumab	No	Yes
IL-6 Inhibitors	Tocilizumab	Yes	No
B-Cell Depletion	Rituximab	Yes	No
T-Cell Co-stimulation	Abatacept	Yes	Yes
IL-23 Inhibitors	Guselkumab	No	Yes

How Clinicians Choose a Biologic 

When transitioning a patient to a biologic, UK rheumatologists consider the “whole person.” If a patient with PsA has very severe skin psoriasis as well as joint pain, the clinician may choose a biologic that is known to have superior results for the skin (like an IL-17 inhibitor), even if a TNF inhibitor is also an option. 

For a patient with RA, the focus is almost entirely on the joints and systemic markers like Rheumatoid Factor. The presence of other health issues, such as inflammatory bowel disease or uveitis, also influences the choice, as some biologics can treat multiple autoimmune conditions simultaneously. In the UK, biosimilars (highly similar, more cost-effective versions of original biologics) are now standard practice for most new prescriptions. 

Conclusion 

There is a significant crossover between the biologics used for RA and PsA, particularly within the TNF inhibitor class. However, because the underlying biology of the two diseases differs, some specialised biologics are reserved for PsA to address both the skin and the joints. Choosing the right biologic is a collaborative process between you and your rheumatology team to ensure all your symptoms are addressed. If you experience a sudden severe allergic reaction after an injection, such as swelling of the throat or difficulty breathing, call 999 immediately. 

Authority Snapshot (E-E-A-T Block) 

This guide provides evidence-based information on biologic treatments for RA and PsA, adhering to UK clinical standards set by the NHS and NICE. The content is authored by the Medical Content Team and reviewed by Dr. Rebecca Fernandez, a UK-trained physician with experience in internal medicine, cardiology, and emergency care. Our aim is to provide safe, factual, and practical information to help the public understand complex autoimmune therapies within the UK healthcare framework.