There is no such thing as washing off Dacronin after 40 minutes of use. Topical application has the effect of relieving localized soft tissue pain and is used to treat sprains, pain in the neck and shoulder area, and so on. Dacronin is a western medicine, commonly used dosage forms are ointment, gel paste, patch and so on. This product is commonly used for external use is the paste, ointment, etc., has the effect of relieving local soft tissue pain, there is no use of 40 minutes and then go to wash off the said, if the wash off will affect the therapeutic efficacy of the drug. Dacronin for external use is commonly used for sports injuries, neck and shoulder pain, pain caused by rheumatoid arthritis. Adverse reactions commonly associated with Dacronin for topical use are occasional rash, itching and burning sensation of the skin.It is contraindicated in children under 15 years of age. Avoid contact with eyes and mucous membranes of the mouth and nose with Dacronin. If necessary, the medication should be used under the supervision of a physician, and it is not recommended to wash it off 40 minutes after use to avoid affecting its therapeutic efficacy.