What is the frequency of diphenhydramine (Benadryl) use?

From the Guidelines

Benadryl (diphenhydramine) should be taken every 4-6 hours as needed for allergy symptoms, with a maximum of 6 doses in 24 hours, and the standard dose is 25-50 mg per dose, not exceeding 300 mg daily, as recommended by the most recent and highest quality study 1.

Key Considerations

• For adults and children 12 years and older, the standard dose is 25-50 mg per dose, not exceeding 300 mg daily.
• Children 6-11 years old should take 12.5-25 mg every 4-6 hours, not exceeding 150 mg daily.
• Benadryl should not be given to children under 6 years without medical advice.
• For sleep aid purposes, adults typically take 50 mg 30 minutes before bedtime.
• This medication works by blocking histamine receptors, which helps reduce allergy symptoms like sneezing, itching, and runny nose, while its sedative effects can help with sleep.
• However, regular use for sleep is not recommended due to tolerance development and side effects like daytime drowsiness, dry mouth, and blurred vision.
• Elderly patients should use lower doses due to increased sensitivity to side effects.

Important Warnings

• Always follow package directions or your doctor's instructions for proper dosing.
• Be aware of potential interactions with other medications, such as sedatives, hypnotics, or antidepressant medication, which may enhance performance impairment from antihistamines.
• Use caution in patients with history of leukopenia or neutropenia, dementia, glaucoma, or seizure disorder.
• Monitor for signs of anticholinergic effects, such as dryness of mouth and eyes, constipation, inhibition of micturition, and an increased risk for provocation of narrow angle glaucoma.

From the FDA Drug Label

Directions • take every 4 to 6 hours, or as directed by a physician• do not take more than 6 doses in 24 hours

• The recommended dosage frequency of Benadryl (diphenhydramine) is every 4 to 6 hours.
• The maximum number of doses allowed in 24 hours is 6 doses 2.

From the Research

Usage of Benadryl

• Benadryl, also known as diphenhydramine, is an antihistamine medication that has been widely used for many years 3.
• However, due to its negative side effects, such as sedation and risk of toxicity in overdose, including cardiac toxicity, it is often inappropriately used when newer, more favorable antihistamine medications are available 3, 4.
• The frequency of Benadryl use is not explicitly stated in the provided studies, but it is mentioned that it is one of the most widely available and longest-used antihistamine medications 3.

Alternatives to Benadryl

• Second-generation antihistamines are widely available and affordable, with many of the same desired effects as diphenhydramine and fewer, if any, of the undesirable side effects 3, 4.
• Countries such as Germany and Sweden have restricted access to first-generation antihistamines, and societal guidelines advocate for the use of second-generation antihistamines 4.

Pharmacokinetics of Diphenhydramine

• The pharmacokinetics of diphenhydramine have been studied in different age groups, including elderly adults, young adults, and children 5.
• The mean serum elimination half-life values for diphenhydramine differed significantly in these age groups, with values of 13.5 +/- 4.2 hours, 9.2 +/- 2.5 hours, and 5.4 +/- 1.8 hours, respectively 5.
• The clearance rates for diphenhydramine also differed significantly with age, being 11.7 +/- 3.1 mL/min/kg in elderly adults, 23.3 +/- 9.4 mL/min/kg in young adults, and 49.2 +/- 22.8 mL/min/kg in children 5.