The first dosage should be given 30 minutes to 1 hour before you travel or begin motion exercise to avoid motion sickness. Dimenhydrinate can be used by adults and children over the age of 12 every 4 to 6 hours as needed to prevent or cure motion sickness. It works mainly by blocking the effects of serotonin called receptor antagonists. Motion sickness can also be prevented by eating small, frequent meals or snacks, staying hydrated, and taking a few minutes at each meal or snack to relax and re-center yourself. Motion sickness is more likely if you are hungry or thirsty, so make sure to eat and drink regularly. Dramamine works faster than dimenhydrinate and is usually given as a single dose before traveling. It may take up to 90 minutes for the full effect to come after taking a dose of this medication. Dimenhydrinate is considered the standard treatment for motion sickness. The usual dose is 0.5 mg/kg body weight given 1 hour before traveling. If necessary, another dose can be given 6 hours later. Children may need one-quarter of the adult dose; do not give doses greater than 2 mg/kg body weight. Dramamine is also recommended for treating nausea and vomiting caused by chemotherapy or radiation therapy. In these cases, it works quickly and is less likely to cause drowsiness than dimenhydrinate.