Diclofenac is an anti-inflammatory used for joint and muscle pain, available as tablets and as gels and rubs. Like all anti-inflammatories it affects the stomach, kidneys and circulation with prolonged use.
One thing distinguishes it within the class: diclofenac taken by mouth is associated with a higher cardiovascular risk than some other anti-inflammatories, particularly at higher doses and over longer periods. That is why it is generally avoided in people with established heart disease, previous stroke, or significant cardiovascular risk factors, and why a different anti-inflammatory is often chosen for anyone needing prolonged treatment.
This applies to tablets. The gel is a different proposition, since far less reaches the bloodstream, which is one reason topical diclofenac is often preferred for localised joint pain. See Voltaren gel side effects.
Common side effects of this pharmacy medicine or category
Indigestion, heartburn, stomach pain, nausea, headache, dizziness and fluid retention. With prolonged use, three systems accumulate risk:
- Stomach. Ulcers and bleeding, which can occur without warning indigestion first. See stomach ulcer risk.
- Kidneys. Reduced kidney function, particularly during dehydration or alongside blood pressure medicines and diuretics. Often silent until found on a blood test. See painkillers and the kidneys.
- Heart and circulation. Raised blood pressure, fluid retention, and a small increase in cardiovascular risk with higher doses over longer periods.
Diclofenac can also raise liver enzymes, so liver blood tests are sometimes checked with longer courses.
Interactions and duplicate-ingredient risks
Do not combine with another anti-inflammatory, including ibuprofen, low-dose aspirin taken for the heart, combination painkillers containing an NSAID, or a diclofenac gel alongside diclofenac tablets.
Blood thinners, steroids and SSRI antidepressants each add to bleeding risk. Blood pressure medicines and diuretics combined with diclofenac add kidney risk. Mention it if you take lithium or methotrexate, whose levels it can raise.
Children, pregnancy, older adults and chronic medicine cautions
- Heart disease, previous heart attack or stroke, heart failure, or significant cardiovascular risk. Oral diclofenac is generally avoided. Ask specifically if you are on it long term.
- Previous ulcer or gut bleed, kidney disease or liver disease.
- Pregnancy. Generally avoided, particularly later in pregnancy.
- Older adults, at higher risk of both bleeding and kidney effects.
- Asthma, where NSAIDs trigger symptoms in a minority.
Warning signs and overdose concerns
Emergency care for chest pain or tightness, sudden breathlessness, one-sided weakness or difficulty speaking, vomiting blood, black tarry stools, or severe abdominal pain.
Same-day advice for passing much less urine than usual, marked swelling, yellowing of the eyes or skin, or new persistent indigestion.
Long-term use reasonably warrants blood pressure, kidney function and liver monitoring, plus a periodic review of whether it is still the right choice.
Questions to ask a pharmacist before using it
- Given my heart history, is oral diclofenac the right choice for me?
- Would the gel work for my pain instead of tablets?
- Do I need stomach protection?
- What monitoring should I have on long-term use?
- Is there a different anti-inflammatory that would suit me better?
Related OTC and medicine-safety guides
- NSAID side effects
- Long-term painkiller side effects
- Chronic pain medication side effects
- When to see a doctor about an OTC medicine
- Report an OTC medicine side effect
See also diclofenac gel and anti-inflammatory tablet 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.