Menthol, the Active Ingredient in Biofreeze

Biofreeze pain relieving gel contains several inactive ingredients, but only one active one, and that is natural menthol. Menthol happens naturally in plants such as cornmint, peppermint, and other mint oils from which it can be extracted, for example by steam distillation of mint leaves. It can also be made synthetically with a more complex, but less expensive process. Menthol has many uses and applications, some of which are exemplified by the properties of Biofreeze. These uses have been known for centuries; in traditional Asian medicine it is used in the treatment of nausea, diarrhea, indigestion, headache, cold, and sore throat.
The versatility of menthol makes it a preferred ingredient in many products other than Biofreeze, including lip balms and cold medicine, as an antipruritic to decrease itching, decongestants, sunburn ointments, aftershave products, mouthwashes, toothpastes, first aid products, beauty products, and as an antispasmodic and smooth muscle relaxant. In the particular case of Biofreeze, menthol is used as a topical analgesic, ideal to alleviate minor pains, for instance those related to muscle cramps, sprains, and headaches. Menthol produces a cooling, soothing sensation when it comes in contact with the skin, achieved by triggering the cold receptors in the body.

Note that the menthol doesn’t actually make the skin cold; it merely persuades it that it feels cold. Menthol is thought to attach to K-opioid receptors, proteins located in the brain, spinal cord and neurons, and which have an influence on how pain is perceived. This cooling sensation, as well as menthol’s anesthetic and counterirritant abilities is what leads to this substance being employed in the treatment of skin irritation, sore throat, nasal congestion, sunburn, fever, and muscle aches. To put it in context, the effect of menthol is similar to that of capsaicin, only that chemical provokes a warm feeling.
More specifically, the counterirritant effect of the menthol in Biofreeze blocks the pain signals sent to the brain, which is a process known as gate control. As a result, the application of Biofreeze on an area afflicted by pain will disrupt the natural cycle of pain signals, meaning that neither the spinal cord nor the brain will perceive that pain caused by an injury, for instance. Cooling has long been linked to analgesia, though this mechanism has not always been properly understood. As science and technology progress products like Biofreeze can make the most of natural resources like menthol.  

Related Read: Is Biofreeze Better Than Ice?