How many Benadryl can you take if you weigh 100 pounds?

The normal dose is 0.5-1mg/kg if you're a child, or child sized... so at 70lbs you're roughly 31kg, so around 30mg should be good for you. If you don't like that much, half it and take 15mg. The normal dose is 0.5-1mg/kg if you're a child, or child sized... so at 70lbs you're roughly 31kg, so around 30mg should be good for you. If you don't like that much, half it and take 15mg.