Things like muscle rub that either give your skin a hot or cold feeling do nothing more than distract you from the pain. Muscle pain is not pleasant but the heat from a muscle rub is either not as unpleasant or actually pleasant and your attention is taken away from the muscle ache and on the heat or cold.
The skin is not an impermeable barrier. While effective at keeping things out, it has holes through sweat glands and very narrow passages between cells. Because of this, medications especially small, lipophilic ones can pass through and enter circulation. The rate of the medication entering can also be altered through heat, surface area, methods to enhance permeability (such as iontophoresis) and other chemicals that increases permeability of the skin (such as alcohol).
They don’t, honestly. Most topical treatments for things like headache or cramps aren’t really that effective. There are other transdermal medicines. Nicotine is a popular one. Other common prescription versions are lidocaine patches, scopolamine patches, and clonidine patches. They stay on for hours, and give steady dose of medicine, and often only need to be changed every few days.
There are some topical medicines that get absorbed and are effective, but many aren’t. Head-On is an example, and is actually a homeopathic medicine that is essentially just wax.
Latest Answers