Do arthritis medications weaken the immune system? 

The short answer is yes, many of the medications used to treat inflammatory types of arthritis, such as Rheumatoid Arthritis (RA) and Psoriatic Arthritis (PsA), work by suppressing or modulating the immune system. Because these conditions are caused by the immune system mistakenly attacking healthy joint tissue, the primary goal of treatment is to “calm” this overactive response. While this is essential for preventing permanent joint damage, it does mean that your body’s natural ability to fight off infections can be reduced. In the UK, rheumatology teams provide specific guidance and regular monitoring to help you balance the benefits of treatment with the risks of immunosuppression. 

What We’ll Discuss in This Article 

• How DMARDs and biologics target the immune system 

• The difference between immunosuppression and immunomodulation 

• Identifying and managing the increased risk of infection 

• The importance of regular blood monitoring (FBC and LFTs) 

• Vaccination safety while on arthritis medication 

• Steps you can take to protect your health while on treatment 

Arthritis medications like DMARDs and biologics weaken the immune system by design, as this is how they stop the inflammation that causes joint pain and destruction. By “dampening” the immune response, these drugs prevent the body from attacking its own joints, but they also make it slightly harder for the body to respond to external threats like bacteria and viruses. The NHS notes that because these medicines affect your immune system, you may be more likely to get infections, and you should seek medical advice if you develop symptoms like a high temperature or a persistent cough. 

How Different Medications Work 

Not all arthritis medications affect the immune system in the same way. In the UK, treatments are typically categorised based on how they interact with your body’s natural defences. 

Conventional DMARDs (e.g., Methotrexate): 

These medications broadly “tamp down” the immune system. Methotrexate, the most common DMARD, slows down the production of certain immune cells to reduce swelling and joint damage. 

Biological Therapies (e.g., Adalimumab, Etanercept): 

These are more targeted. They block specific proteins in the blood (such as TNF-alpha or Interleukins) that act as “messengers” to trigger inflammation. While more precise, they still lower your overall immune response. 

JAK Inhibitors: 

These are a newer class of “targeted synthetic” DMARDs that block the signaling pathways inside immune cells, preventing them from starting the inflammatory process. 

Steroids (e.g., Prednisolone): 

These provide powerful, broad immunosuppression and are usually used as a short-term “bridge” to manage severe flares.

Understanding Infection Risk 

Because your immune system is less active, common infections, such as the flu, urinary tract infections (UTIs), or skin infections, can sometimes become more serious or take longer to clear.¹² In the UK, patients on biologics are also screened for “latent” infections like Tuberculosis (TB) before starting treatment, as the medication could cause a dormant infection to become active again.  

You should contact your GP or rheumatology nurse if you experience: 

1. A high temperature or fever. 

2. Feeling “shivery” or generally unwell. 

3. A sore throat or cough that won’t go away. 

4. Burning when you pass urine. 

5. A wound or cut that becomes red, hot, and swollen. 

The National Institute for Health and Care Excellence provides clear safety protocols for monitoring patients on immunosuppressive therapy to ensure infections are caught and treated early. 

Blood Monitoring and Safety 

To manage the risks of a weakened immune system, the NHS uses a strict blood monitoring schedule. These tests check your “Full Blood Count” (FBC) to ensure your white blood cell levels (the cells that fight infection) do not drop too low. If your white cell count falls below a certain level, your rheumatologist may ask you to pause your medication temporarily. 

Medication Type	Common Monitoring	Key Safety Concern
Methotrexate	FBC and Liver Function	Low white cell count / liver stress
Biologics	FBC and TB Screening	Serious infections / TB reactivation
JAK Inhibitors	FBC and Cholesterol	Infection / blood clot risk
Sulfasalazine	FBC	Impact on blood cell production

Vaccinations and Arthritis Medication 

Maintaining your immunity through vaccinations is vital when you are on immunosuppressive drugs.¹⁴ However, there is an important distinction between “live” and “non-live” vaccines. 

Non-Live Vaccines (Safe): 

The annual flu jab, the COVID-19 vaccine, and the pneumonia vaccine are safe and highly recommended for people on DMARDs or biologics in the UK. 

Live Vaccines (Caution): 

Vaccines like the yellow fever or the shingles vaccine (the live version) are generally avoided while on biologics or high-dose steroids, as they contain a weakened version of the actual virus. Always discuss your vaccination schedule with your rheumatology team to ensure you are receiving the safest versions available. 

Conclusion 

Arthritis medications do weaken the immune system, but this is a necessary trade-off to prevent the life-altering joint damage caused by autoimmune inflammation.¹⁵ While you are at a slightly higher risk of infection, the vast majority of people manage this safely through regular blood tests, staying up to date with non-live vaccinations, and practicing good hygiene. If you develop signs of a severe infection, such as confusion, a very high fever, or difficulty breathing, call 999 or go to A&E immediately. 

Authority Snapshot (E-E-A-T Block) 

This guide provides evidence-based information on how arthritis medications affect the immune system, following clinical standards from the NHS, NICE, and the British Society for Rheumatology. The content is authored by the Medical Content Team and reviewed by Dr. Rebecca Fernandez, a UK-trained physician with experience in internal medicine and emergency care. Our goal is to provide safe, factual, and practical information to help patients manage their autoimmune treatments effectively.