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What are Topical Pain Relievers?
Topical pain relievers come in a variety of different types. Most of us are familiar with the rub on creams which can be purchased over the counter without a prescription. These are applied directly to the source of the pain, such as Biofreeze. But topical pain relievers can also be bought as patches and heat wraps or ice packs.
How do they work?
Pain is felt as a series of nerve signals from local receptors which are sent directly into the nervous system. The sharp pain of a pin-prick or burn is felt almost instantaneously and the human body has compensatory mechanisms for dealing with such a signal. We immediately withdraw our hands from the pain. We do this sub consciously, without even thinking about it.
But the constant, unrelenting pain of an inflamed joint or an aching muscle does not have a quick resolution. It can be caused by a sudden problem such as an inflamed joint or even be a sign that there is a disease process going on, for example arthritis or fibromyalgia. Or it can signal a host of other types of conditions such as sprained muscles or tendons and pulled ligaments.
While oral analgesics work by numbing the signal and stopping it from reaching the brain, topical pain relievers often work by blunting this signal or sending compensatory signals. So, a nice warm heat pack can stimulate heat receptors in the skin which also fire off nerve transmissions to the brain and the message of pain becomes diluted. According to WebMD, they can actually work in three different ways:
These are derived from aspirin and can be absorbed through the skin and act as a local pain killer. They sit between the pain receptors and the nerve endings and prevent the signal from being transferred. These work best when the source of the pain is close to the skin. So the best application of this would be in a finger joint for example which can easily absorb the medicine. Examples of these include Bengay and Aspercreme.
Anything which causes a slight burning or warming feeling in the skin around the pain is a counter-irritant. For example a medicine which contains menthol creates a glowing, buzzing feeling in the skin which blunts the feeling of pain. Types of cream which contain menthol are Flexall 454, Icy Hot and JointFlex.
Capsaicin, which is derived from the pepper plant, has a similar effect and is one of the most effective products available for topical pain relief. Applying creams which contain this chemical causes a mild tingling, or gentle warming sensation on the skin. This again helps to mask the feeling of the pain itself and may even have anti inflammatory effects. Creams containing capsaicin work on lowering a chemical called Substance P which is found in the nerve cells. This usually helps to send nerve signals from receptors to the brain. Zostrix, ArthriCare and Capzasin contain capsaicin as the active ingredient.