Veterinarians use diphenhydramine, commonly known by the brand name Benadryl, for dogs on a regular basis to treat allergies, travel anxiety, and motion sickness. However, some human medications are safe for use with dogs, as long as they are used appropriately. Humans and dogs react very differently to medications, which is why veterinarians caution dog owners against making independent decisions about how to medicate their animals. The temptation to reach into our medicine cabinets to treat our pets can be dangerous.