How much benadryl should you take if you weigh 150 pounds?

For adults, the typical dosage of Benadryl (diphenhydramine) for allergy relief is 25 to 50 mg every 4 to 6 hours, not exceeding 300 mg in a 24-hour period. Weight does not significantly alter the standard dosing for this medication. However, it's always best to consult with a healthcare professional before taking any medication to ensure it's appropriate for your specific situation.