<unk> (synthetic), menthol and methyl salicylate plaster is an external analgesic that is FDA approved for the treatment of simple backache,arthritis,strains,bruises,sprains.   Common adverse reactions include seizures, nausea , vomiting, warmth ,headache  , confusion ,vertigo, delirium, hallucinations,tremors,
contact eczema.
Camphor 
Dimethylphthalate
Coal tar
Tetrachloroethylene
Cyclohexane
Trichloroethylene
Triphenylmethane
Nitrazine