Deep Heat, Counterpain, Salonpas, Tiger Balm, and the various menthol sprays sold in every pharmacy here.
They’re cheap, effective for what they do, and combining them with a heat pad is one of the easiest ways to burn yourself.
Most “heat” rubs don’t produce heat
This is the part that surprises people.
A menthol or capsicum rub doesn’t raise the temperature of your skin. It stimulates the nerve endings that report hot or cold, so your brain registers warmth that isn’t there at all(!).
That’s a real and useful effect: the sensation competes with the pain signal, which is why the area feels better for a while. Warmth from a pad does that too, but it also raises tissue temperature: see what heat actually does under your skin.
But no heat is being delivered!
Which means your normal sense of how hot something feels stops being a reliable guide.
Why the combination burns
Three problems stack up:
- Your warning system is confused. The skin already feels warm or tingly from the rub, so the extra heat from a pad doesn’t register as clearly. That’s the same failure mode as reduced sensation, just temporary and self-inflicted.
- Heat increases absorption. Warming the skin increases how much of an applied product gets through it. That’s true of counter-irritant rubs and of medicated patches containing an anti-inflammatory drug.
- The area is already irritated. These products work by irritating the skin. Adding heat to irritated skin is how you get blistering.
Manufacturers of these products say not to apply heat over them, and burn units see the results when people do. Capsicum-based products, the chilli-derived ones, are the most likely to cause a significant burn.
The rule
Use one or the other, never both on the same area.
If you’ve used a rub or patch and want to use a heat pad instead, wash the area thoroughly with soap and water and wait until the tingling has completely gone. Several hours is sensible.
Same applies in reverse. Don’t apply a rub straight after heating the area, when the skin is warm and more absorbent.
Which to choose
- A rub or patch suits being out of the house, or a spot you can’t easily rest a pad on. It’s portable and needs no socket.
- A heat pad suits genuinely warming tight muscle before stretching or exercise, which a rub can’t do. Real warmth increases tissue extensibility; the sensation of warmth doesn’t. See “my physio said use heat” — but how, exactly?
For loosening a stiff back before your exercises, the pad. For getting through an afternoon at work, the patch. More: heat pads vs heat patches, and the wider comparison in electric vs microwave vs stick-on heat packs.
Other cautions with rubs and patches
- Wash your hands afterwards. Getting menthol or capsicum in your eyes is memorable.
- Never on broken skin or a rash.
- Not under tight bandaging, which increases absorption the same way heat does.
- Not before a hot shower or bath. Same problem as the pad.
- Don’t sleep in a patch. Hours of unbroken contact is its own burn risk: is it safe to sleep with a heating pad on?
- Medicated patches are medicine. If you’re already taking anti-inflammatory tablets, or have asthma, stomach or kidney problems, ask a pharmacist before using one.
- Keep them away from children and pets, used ones included. Fold a used patch sticky sides together before binning it. See heat pads and children.
- Not on anyone with reduced sensation. Same reasoning as heat. See who should not use a heating pad.
If you’ve burned yourself
Wash the product off with soap and water, then cool the area under running water for 20 minutes. See a doctor if there’s blistering, if the burn is larger than a coin, or if it’s still painful hours later. Burns from this combination are often deeper than they look, much like the slow damage from daily heat on one spot.
Clinically reviewed by: Nigel Chua (Hand Occupational Therapist) & Louise Yow (Physiotherapist). This article is general information, not a diagnosis. electricheatpad.com sells electric heat pads.
