How much bendrly to give a 2 1/2 year old?

Benadryl (diphenhydramine) dose. Benadryl (diphenhydramine) comes as 12.5 mg/5 ml concentration. A 2 1/2 year old (28 lbs 9 oz--32 lb 12oz) should take 7 (seven) ml [use a calibrated dose giver] every 6 hours. If your child does not fall into that weight range, re-ask the question with the child's weight since pediatric doses are based on weight.
Benadryl (diphenhydramine) I assume you ask about Benadryl (diphenhydramine) dosage.Depend on your child weight-it would be 1tsp(5ml) for 29-41 lbs with Benadryl (diphenhydramine) liquid 12.5mg/5ml every 4-6 hours as needed or. Will be less 2.5 ml with 12-20lbs every 4-6 hours as needed.