What side effects are common with RA or PsA medications?
Managing Rheumatoid Arthritis (RA) and Psoriatic Arthritis (PsA) involves using powerful medications that modify the immune system to prevent joint damage. While these treatments are essential for long-term health, they can cause a range of side effects as the body adjusts to the medication. Understanding what to expect and which symptoms require medical attention is a vital part of safely managing your condition. This guide outlines the common side effects associated with the primary classes of arthritis medication used in the UK and the monitoring protocols in place to keep you safe.
What We’ll Discuss in This Article
- Common side effects of conventional DMARDs like methotrexate
- The impact of biological treatments on the immune system
- Gastrointestinal and systemic side effects of anti-inflammatories
- Why regular blood tests are required for safety monitoring
- Significant “red flag” symptoms that require urgent medical review
- How side effects are managed and when medications may be adjusted
Most side effects of RA and PsA medications are mild and often improve as the body becomes accustomed to the treatment, but because these drugs work by suppressing the immune system, they carry specific risks related to infections and organ function. Conventional treatments like methotrexate frequently cause gastrointestinal upset or fatigue, while biological therapies may lead to skin reactions at the injection site. The NHS states that common side effects of methotrexate include feeling sick, loss of appetite, a sore mouth, diarrhoea, and headaches.
Side Effects of Conventional DMARDs
Conventional Disease-Modifying Anti-Rheumatic Drugs (DMARDs) are often the first line of treatment. Methotrexate is the most commonly prescribed drug in this category, and while it is highly effective, it is known for causing nausea and a general feeling of being unwell, particularly in the 24 to 48 hours following the weekly dose. To help manage these symptoms, doctors almost always prescribe folic acid to be taken on the days you are not taking methotrexate.
Other conventional DMARDs, such as sulfasalazine or leflunomide, can cause different issues. Sulfasalazine may cause a temporary orange discolouration of urine or tears, which is harmless but can be surprising if unexpected. Leflunomide can sometimes lead to an increase in blood pressure or thinning of the hair. Because these medications can affect the liver and bone marrow, patients must follow a strict schedule of blood tests to ensure their internal organs are functioning correctly.
Biological and Targeted Synthetic Therapies
Biological treatments, such as adalimumab or etanercept, target very specific proteins in the immune system. Because they are given by injection, the most common side effect is a localized skin reaction, such as redness, itching, or swelling where the needle entered the skin. These reactions are usually mild and tend to resolve within a few days.
A more significant side effect of all biological and targeted synthetic drugs (like JAK inhibitors) is an increased susceptibility to infections. Because these drugs dampen the immune response, a common cold can sometimes become more severe, or a dormant infection like tuberculosis could be reactivated. The NHS explains that side effects from biological treatments are usually mild but include skin reactions at the site of injections, infections, feeling sick, and a high temperature.
Anti-Inflammatories and Steroids
Non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids are used for rapid symptom relief, but they carry their own sets of side effects, particularly with long-term use. NSAIDs like ibuprofen or naproxen can irritate the stomach lining, potentially leading to indigestion or, in more severe cases, stomach ulcers. To protect the stomach, GPs often prescribe a proton pump inhibitor (PPI) alongside these medications.
Corticosteroids, such as prednisolone, are extremely effective for flares but can cause systemic side effects if used for long periods. These include weight gain, a “rounding” of the face, mood changes, and a thinning of the bones known as osteoporosis. Because of these risks, steroids are typically used at the lowest possible dose for the shortest time necessary to settle a flare-up.
Comparison of Side Effects by Drug Class
The following table provides a summary of the most frequent side effects associated with the different categories of arthritis medication.
| Drug Class | Common Side Effects | Key Safety Note |
| Conventional DMARDs | Nausea, fatigue, mouth sores | Requires regular blood tests |
| Biologicals | Injection site redness, infections | Screen for TB before starting |
| JAK Inhibitors | Shingles risk, nausea | Monitor cholesterol levels |
| NSAIDs | Indigestion, stomach irritation | Take with food and a PPI |
| Corticosteroids | Weight gain, sleep issues | Do not stop abruptly |
Monitoring and “Red Flag” Symptoms
The UK healthcare system uses a “shared care” approach to monitor medication safety. This means your specialist and GP work together to conduct regular blood tests, initially every two weeks and eventually every three months once you are stable. These tests check your Full Blood Count (FBC) and Liver Function Tests (LFTs) to catch any early signs of toxicity before you feel physically unwell.
There are certain symptoms that should never be ignored while taking these medications. If you develop a high fever, a persistent sore throat, unexplained bruising, or a sudden dry cough and shortness of breath, you must contact your rheumatology team or GP immediately. These can be signs that the medication is affecting your blood cells or lungs, and the drug may need to be paused while the cause is investigated.
Conclusion
While side effects are common with RA and PsA medications, most are manageable and occur as the body adapts to the treatment. The risk of side effects is carefully balanced against the much higher risk of permanent joint damage if the arthritis is left untreated. By attending regular monitoring appointments and reporting any new symptoms to your clinical team, you can use these essential medications safely and effectively. If you experience severe, sudden, or worsening symptoms, call 999 immediately.
Why do I feel so tired after my methotrexate dose?
This is often called a “methotrexate hangover” and is a common systemic side effect; taking your dose in the evening or ensuring you take your folic acid can help.
Is it normal for my urine to turn orange on sulfasalazine?
Yes, this is a completely harmless side effect of the medication and is not a cause for concern.
What should I do if I get a cold while on a biologic?
If you have a fever or need antibiotics, you should usually pause your biologic treatment until you are well; always contact your specialist nurse for guidance.
Can RA medications cause my hair to thin?
Some DMARDs like methotrexate or leflunomide can cause mild hair thinning in some people, which usually improves if the dose is adjusted.
Why do I need to avoid alcohol on these medications?
Both methotrexate and alcohol are processed by the liver; consuming too much alcohol can significantly increase the risk of liver damage.
Will I always have nausea when I start a new drug?
Nausea is common in the first few weeks, but it often settles down. Taking tablets with a large meal can often help reduce this feeling.
Can these medications affect my mood?
Steroids are well-known for causing mood swings or irritability, but most other arthritis medications do not typically have a direct effect on your mood.
Authority Snapshot (E-E-A-T Block)
This guide provides evidence-based information on the side effects of arthritis medications, strictly following NHS and NICE clinical safety standards. The content is authored by the Medical Content Team and reviewed by Dr. Rebecca Fernandez, a UK-trained physician with extensive experience in internal medicine and emergency care. We aim to provide accurate and transparent information to help patients recognize and manage potential side effects safely within the UK healthcare framework.
