NSAIDs, or non-steroidal anti-inflammatory drugs, include ibuprofen, diclofenac, naproxen and aspirin, plus the gels and rubs applied to the skin. They reduce pain, inflammation and fever, and they share a single mechanism, which is why they also share a predictable set of risks.
That mechanism blocks chemicals that cause inflammation. The same chemicals protect the stomach lining and help regulate blood flow through the kidneys, which is where the main problems come from. Understanding that one fact explains almost everything on this page.
Common side effects of this pharmacy medicine or category
- Indigestion, heartburn, stomach pain or nausea
- Diarrhoea or constipation
- Headache and dizziness
- Fluid retention and mild ankle swelling
- Raised blood pressure
- Rash
The four risks that matter beyond everyday discomfort:
- Stomach ulcers and bleeding, which can develop without warning indigestion first, particularly in older adults. See signs of stomach bleeding.
- Kidney effects, especially during dehydration or alongside certain blood pressure medicines. See painkillers and the kidneys.
- Cardiovascular risk, a small increase with higher doses and prolonged use.
- Asthma. A minority of people with asthma react to NSAIDs with wheeze or worsening symptoms.
Topical gels carry lower systemic risk than tablets because less is absorbed, but they are still NSAIDs and still count towards your total. See diclofenac gel and Voltaren gel.
Interactions and duplicate-ingredient risks
Never take two NSAIDs together. This includes a tablet plus a gel, a combination painkiller that already contains one, and low-dose aspirin taken for the heart, which is itself an NSAID.
- Blood thinners such as warfarin and clopidogrel: substantially higher bleeding risk.
- Corticosteroids such as prednisone: markedly higher ulcer risk.
- SSRI antidepressants: added bleeding risk.
- Blood pressure medicines and diuretics. The combination of an ACE inhibitor or ARB, a diuretic and an NSAID is a recognised cause of kidney injury, particularly during dehydration.
- Lithium and methotrexate: NSAIDs can raise levels of both. See lithium and methotrexate.
Children, pregnancy, older adults and chronic medicine cautions
- Pregnancy. Generally avoided, particularly in later pregnancy. Ask before taking any NSAID.
- Older adults. Higher risk of both bleeding and kidney effects, often without early warning.
- Previous ulcer or bleed. Usually a reason to avoid NSAIDs or to use stomach protection alongside.
- Kidney disease, heart failure or liver disease. Ask first in each case.
- Dehydration. During vomiting, diarrhoea or heavy exertion, NSAIDs strain the kidneys further.
- Children. Ibuprofen is dosed by weight and fluids should be kept up. See children’s ibuprofen.
Warning signs and overdose concerns
Emergency care for: vomiting blood or material like coffee grounds; black tarry stools; severe or sudden abdominal pain; difficulty breathing, wheeze or facial swelling; a rash that blisters or peels.
Same-day advice for: passing much less urine than usual, marked swelling of the legs or face, yellowing of the eyes or skin, or new persistent indigestion.
Questions to ask a pharmacist before using it
- Is an NSAID suitable for me, or would paracetamol be safer?
- Do I need something to protect my stomach?
- Does anything else I take contain an NSAID?
- Would a gel be a better option than tablets for this?
- How many days can I use it before review?
Related OTC and medicine-safety guides
- OTC medicine side effects
- Painkiller side effects
- How to read over-the-counter medicine labels
- When to see a doctor about an OTC medicine
- Report an OTC medicine side effect
See also anti-inflammatory tablet side effects and ibuprofen side effects.
Medical Disclaimer: This content is for informational and educational purposes only and does not constitute medical diagnosis, prescription, or professional advice. Always read the patient information leaflet and consult a qualified doctor or pharmacist regarding any medicine or health concern.