Menthol-based topical pain relievers like Biofreeze are clinically researched and have traditionally been recommended for pain relief purposes by clinicians and peers alike. Nevertheless, some may not be convinced that a topical pain reliever can work. Researchers Anderson and colleagues established a study to help give clinicians piece of mind. “This study aimed to characterize the effect of menthol as a counterirritant on cutaneous pain and hyperalgesia provoked by topical application oftrans-cinnamaldehyde” (Anderson HH et al 2016).
The validity of menthol pain relief
Fourteen healthy patients received an application of trans-cinnamaldehyde on the forearm to induce neurogenic inflammation, pain, mechanical, and thermal hyperalgesia (an increased sensitivity to pain). 10% trans-cinnamaldehyde was applied alone or with 40% menthol applied simultaneously for 20 minutes. Each participant logged his or her pain intensity while a sensory test and superficial blood flow (neurogenic inflammation) was recorded.
The application of trans-cinnamaldehyde evoked its intended side effects. Patients who had topical menthol co-administered found a reduction in:
- Spontaneous pain intensity
- Neurogenic inflammation
- Primary and secondary mechanical hyperalgesia, and heat hyperalgesia
However, the menthol was not successful in reducing cold hyperalgesia.
Because of the success of its inhibitory effects, the researchers concluded that menthol could be useful as topical solution to decrease sensitivity to pain and are “of great therapeutic potential” (Anderson HH et al 2016). More importantly, this study supported the “Gate Control Theory” of pain relief in a human model using topical menthol.
Andersen HH et al 2016. High-Concentration L-Menthol Exhibits Counter-Irritancy to Neurogenic Inflammation, Thermal and Mechanical Hyperalgesia Caused by Trans-cinnamaldehyde. J Pain. Aug;17(8):919-29.