One of two anti-inflammatory drugs may be found in topical pain relievers available without a prescription: a nonsteroidal anti-inflammatory (diclofenac) or a salicylate (trolamine salicylate, an aspirin derivative).
Applying these products to the skin allows the medication to act only on the site of the pain and avoid certain adverse side effects, such as stomach irritation, that may arise when this type of medication is taken orally.
Products containing counterirritants such as camphor, menthol, eucalyptus, methyl salicylate, and capsaicin cause mild skin irritation or inflammation accompanied by a feeling of heat or cold. This means you do not feel the pain as much, as your brain is momentarily occupied by this new sensation.
It is a common misconception that topical pain relievers will not affect your body like oral medications do. Parts of topical pain reliever ingredients will be absorbed through your skin and enter into your blood circulation. For this reason, people who are advised to avoid taking nonsteroidal anti-inflammatories (NSAID) or salicylates orally because of an allergy or other reasons should also stay away from topical products that contain them.
Always validate with the pharmacist before using a topical analgesic in conjunction with another type of pain medication, some products may not be compatible or there may be a risk of an accidental overdose.
Regardless of the product you use, it is important to apply it to skin that is clean, and dry. Do not apply on open wounds or irritated skin. Help the medication work better by slowly rubbing it in (except for patches). Wash hands thoroughly after applying, to avoid getting the product in your eyes or mouth. Do not apply bandages or heat, like heating pads, to the treated area, as this increases the risk of skin irritation and burns.
When in doubt, your pharmacist can help you choose the product that best suits your needs.