Suggest Emeset Dosage For The Treatment Of Motion Sickness

Hi, Our kids feel motion sickness during Sea travel. We used to give emeset to them previously. However as their weight has changed we do not know the dosage for them now. What’s the right dose for Emeset syrup (2mg), for a 2 year old (10kg) and 4 year old (18kg)? And how long before should the medicine be taken before travel and is there a time between intake of emeset and intake of any food?