Dramamine (dimenhydrinate) and Benadryl (diphenhydramine) are closely related; in fact, Dramamine partly consists of a salt of Benadryl. As a result, they have similar modes of action - they both cross the blood-brain barrier and have anticholinergic properties, which is what helps prevent motion sickness. Unfortunately, the anticholinergic properties of both drugs are what also causes the drowsiness.
As for one of the previous posts mentioning Claritin: although Claritin is an antihistamine, it doesn't cross the blood-brain barrier, which is why it doesn't cause drowsiness, and thus also doesn't affect the nausea center in the brain. I definitely would NOT recommend using Claritin for motion sickness.
Additionally: I should point out that there's a difference between motion sickness and vomiting. If you're already puking from motion sickness, then there's a less likely chance that taking anti-motion-sickness meds like Dramamine will help. The goal is to PREVENT motion sickness before you actually get sick.
As for one of the previous posts mentioning Claritin: although Claritin is an antihistamine, it doesn't cross the blood-brain barrier, which is why it doesn't cause drowsiness, and thus also doesn't affect the nausea center in the brain. I definitely would NOT recommend using Claritin for motion sickness.
Additionally: I should point out that there's a difference between motion sickness and vomiting. If you're already puking from motion sickness, then there's a less likely chance that taking anti-motion-sickness meds like Dramamine will help. The goal is to PREVENT motion sickness before you actually get sick.