Peppermint oil has scientific support for its use in relieving tension, particularly tension-type headaches. The evidence is based on several clinical trials and systematic reviews. Most notably, topical application of peppermint oil (usually in a 10% solution) to the temples and forehead has been shown to reduce headache intensity and provide relief comparable to standard over-the-counter analgesics, such as acetaminophen. The primary mechanism is believed to involve menthol, the main active component of peppermint oil. Menthol has a counter-irritant effect that stimulates the cold receptors in the skin, producing a cooling sensation that can inhibit pain signals and relax underlying muscle contractions.

A frequently cited randomized controlled trial published in Cephalalgia (1996) demonstrated that a 10% peppermint oil solution significantly reduced headache pain compared to placebo, with effects noticeable within 15 minutes and lasting up to an hour. Systematic reviews and meta-analyses, including those by the American Headache Society, have acknowledged peppermint oil's efficacy and safety profile for mild to moderate tension-type headaches. Side effects are minimal when used topically, though it should not be applied near the eyes or to broken skin.

In conclusion, peppermint oil has a solid scientific basis for its traditional and modern use in managing tension, particularly in the context of headaches, and is regarded as an effective, safe, and accessible non-pharmacological intervention.