According to Reference.com, dogs have different medical needs than humans, so they should not typically be given medication prescribed for humans, such as Benadryl or other mild sedatives. To understand which human medications are acceptable, one should seek a veterinarian's professional opinion. A veterinarian may recommend other options, including over-the-counter medications. These include traditional and herbal remedies that work well to ease your pet's hyperactivity, irritability or anxiety.
According to Pet Education, diazepam, more commonly known as Valium, is commonly prescribed by veterinarians to sedate dogs before potentially traumatic experiences such as surgery. This is recommended in high-stress situations where a dog is terrified and unable to relax on its own before the event.
Melatonin-based sedatives can be purchased over the counter to help calm a dog with severe anxiety. The sedation lasts only for a few hours, so this would be ideal for a dog with noise anxiety, such as fear of thunderstorms or fireworks, or anxiety about traveling in a car.
There are many herbal remedies that provide equally good results for dogs suffering from anxiety, fear or over-excitability. According to What Grandma Knew, studies show that Valerian root and chamomile are both highly useful in calming the central nervous system. Either herb can be brewed in a tea and given to dogs suffering from separation anxiety or hyperactivity, but only on a temporary basis.