Find out how much Benadryl adults and children can safely take, plus essential safety tips and side effects to watch for in this medically-reviewed guide. Official answer: The maximum safe Benadryl (diphenhydramine) dose for adults is 50 to 100 mg for a single dose with a daily maximum of. There are other medicines like diphenhydramine that might be safer for young children. The table* below can help you figure out the right amount of diphenhydramine to give. Use your child's weight to decide on the right amount. You can find the weight in the top row of the chart. Find BENADRYL® dosage information for adults, children, and toddlers and learn how much you and your family should take with our allergy medicine product-dosing guide. For adults with common cold symptoms, the typical dosage of Benadryl is 25 to 50 mg (one to two tablets) taken every 4 to 6 hours, or as directed by your doctor. The recommended adult Benadryl dosage for allergies is 1 to 2 tablets or capsules by mouth every 4 to 6 hours as needed. You shouldn’t take more than 6 doses (300 mg) in a 24-hour period. Understanding the correct Benadryl dosage children need is crucial for their safety and recovery. It is a staple in many medicine cabinets, but it is not a “cure-all” and certainly requires respect regarding dosing.