Bio-temper pain relief uses cold therapy to soothe or heal aches and pains and to reduce swelling, pain, and nerve activity. It works by numbing pain and relaxing muscles through the cooling effect of menthol. Pain relief gels can be used to provide relief from pain due to arthritis, muscle ache and soreness, back pain, plantar fasciitis, sciatica, carpal tunnel, tendinitis, sprains and strains, migraines, headaches, menstrual cramps, and fibromyalgia.