What is the active ingredient in Bengay (methyl salicylate and menthol)?

Active Ingredients in Bengay

The active ingredients in Bengay are methyl salicylate (40%), menthol (16%), and camphor (10%). 1

Primary Active Ingredients

• Methyl salicylate (40%) - A topical analgesic that provides pain relief through its anti-inflammatory properties 1, 2
• Menthol (16%) - Provides cooling sensation and acts as a counterirritant that helps suppress the cough reflex and provides pain relief 3, 1
• Camphor (10%) - Works as a mild local anesthetic and antimicrobial agent 1, 4

Mechanism of Action

• Methyl salicylate works as a topical analgesic by penetrating the skin and providing local anti-inflammatory effects 5
• When applied topically, approximately 0.8% of methyl salicylate penetrates the skin with increasing concentration over time 5
• Menthol creates a cooling sensation by activating TRPM8 receptors in the skin, which provides a counterirritant effect 3
• The combination of these ingredients produces vasodilation, which can improve local blood flow to affected areas 6

Clinical Applications

• Bengay and similar products containing methyl salicylate and menthol are commonly used for:
  • Soft tissue pain including shoulder and neck pain 7
  • Back pain and muscle pain 7
  • Temporary relief during flares of erythromelalgia 3

Safety Considerations

• Systemic absorption of topical methyl salicylate is relatively low, even with extended application 4
• The most common adverse reactions include:
  • Local pruritus (0.48% of users) 7
  • Burning sensation at application site (0.28% of users) 7
  • Local irritation (0.2% of users) 7
• Caution should be exercised when using products containing salicylates in:
  • Children under 12 years of age due to increased risk of salicylate toxicity 3
  • Patients taking oral salicylate medications due to potential additive effects 3
  • Pregnant women (Pregnancy Category C) 3

Pharmacokinetics

• After topical application, the average maximum plasma concentrations (with 8 patches) were:
  • Methyl salicylate: 29.5 ± 10.5 ng/mL 4
  • Menthol: 31.9 ± 8.8 ng/mL 4
  • Camphor: 41.0 ± 5.8 ng/mL 4
• Terminal half-lives:
  • Methyl salicylate: 3.0 ± 1.2 hours 4
  • Menthol: 4.7 ± 1.6 hours 4
  • Camphor: 5.6 ± 1.3 hours 4

Important Precautions

• Do not use with other salicylate drugs to avoid potential systemic toxicity 3
• Avoid application to more than 20% of body surface area, especially in patients with abnormal hepatic or renal function 3
• Should not be applied before UVB phototherapy as it may decrease efficacy due to filtering effect 3
• Not recommended for nursing mothers; if used, avoid applying to chest area 3