How long it takes for Difenidol Hydrochloride tablets to take effect is related to the condition, in most cases it takes effect half an hour after taking the medicine. Difenidol Hydrochloride Tablets, the main ingredient of which is methylphenidate hydrochloride, can regulate vestibular function, improve the blood supply of vertebral arteries, used for the prevention and treatment of motion sickness, relief of vertigo, nausea, vomiting and other symptoms when traveling by car or boat. The medicine is usually taken half an hour before traveling by car or boat, and the effect starts half an hour after taking the medicine, and the effect can be maintained for about 4 hours. Difenidol Hydrochloride Tablets should be used under the supervision of a physician, and is contraindicated in case of allergy to this drug. When adverse reactions such as decreased blood pressure, dry mouth, dyspepsia, stomach upset, hallucinations, disorientation, fatigue, headache, etc. occur, the drug should be stopped immediately, and the symptoms can be relieved, and in serious cases, consult a doctor for examination.