Muscle rubs and heat creams are applied for aches, strains and stiffness. Most work by producing a sensation of warmth or cooling that distracts from the pain rather than by treating the underlying problem, which is worth knowing when judging whether one is working.
Typical ingredients include menthol, camphor and methyl salicylate. Some products instead contain an anti-inflammatory such as diclofenac, which works differently. Check which yours is, because the cautions differ. See pain relief gel side effects.
Common side effects of this pharmacy medicine or category
- Warmth, tingling or a burning sensation, which is the intended effect
- Redness of the skin
- Itching or a rash
- Strong smell, which some find unpleasant
Skin burns are the effect worth taking seriously. They are uncommon but well documented, and they usually happen in a predictable way: applying too much, covering the area with a dressing or tight clothing, or using a heat pad, hot water bottle or hot bath over treated skin. The warming sensation masks the fact that real damage is occurring.
Do not combine a heat rub with any external heat source, and do not cover the area unless the label says to.
Interactions and duplicate-ingredient risks
Methyl salicylate is chemically related to aspirin and is absorbed through the skin. Applied heavily, over a large area, or repeatedly, it can add to the effect of aspirin or blood thinners. If you take warfarin or another anticoagulant, mention that you use a muscle rub, since it is exactly the kind of product people do not think to declare.
If your rub contains an anti-inflammatory such as diclofenac, it counts as an NSAID and should not be combined with anti-inflammatory tablets. See NSAID side effects.
Wash your hands thoroughly after applying, and keep it away from eyes, mouth, broken skin and genitals.
Children, pregnancy, older adults and chronic medicine cautions
- Children. Products containing methyl salicylate or camphor are generally not suitable for young children. Ask before using anything on a child.
- Pregnancy and breastfeeding. Check first, particularly for salicylate-containing products, and avoid applying where a baby feeds.
- Reduced skin sensation, for example from diabetes-related nerve damage, where a burn may not be felt until it has happened.
- Asthma, where salicylates occasionally trigger symptoms in sensitive people.
- Older adults, whose thinner skin is more easily damaged.
Warning signs and overdose concerns
Wash the product off and seek advice for pain that intensifies rather than easing, blistering, or skin that looks burned.
Get emergency help for difficulty breathing, wheeze, or swelling of the face, lips or throat, and if a child has swallowed any, since concentrated salicylate products are dangerous if ingested.
See a doctor if the pain lasts beyond the period on the label, follows an injury, comes with swelling or inability to bear weight, or is accompanied by numbness or weakness. A rub relieves a sensation; it does not treat a torn muscle or a joint problem.
Questions to ask a pharmacist before using it
- What is in this one, and does it contain a salicylate or an anti-inflammatory?
- Is it safe with my blood thinner?
- Can I use a heat pad on the same area?
- Is it suitable for my child?
- Would something else work better for this kind of pain?
Related OTC and medicine-safety guides
- Topical medicine side effects
- OTC medicine side effects
- Over-the-counter medicine interactions
- When to see a doctor about an OTC medicine
- Report an OTC medicine side effect
See also Deep Heat and muscle and joint medicine 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.