How Long Does It Take For Benadryl To Work?

Thanks for reaching out! Benadryl (diphenhydramine) is a sedating, first-generation antihistamine and is commonly used for a variety of indications, including:

• Allergies
• Allergic reactions
• Insomnia
• Motion sickness

Benadryl begins to work about 30 minutes after taking it by mouth. However, the maximum sedative effects of Benadryl are generally seen 1 to 3 hours after taking by mouth. Therefore, if you are taking Benadryl to help you sleep, you want to take it at least 30 minutes before bedtime.

Although the duration of action can vary by individual, Benadryl generally lasts around 4 to 6 hours per dose. This can be prolonged in the elderly or in those with liver disease.

Benadryl Indications

Although Benadryl can be used for seasonal allergy symptoms, it is generally utilized more often for the treatment of insomnia and allergic reactions. For seasonal allergy symptoms, second-generation antihistamines such as Claritin and Allegra may be better options as they are non-drowsy and last for 24 hours per dose.

Benadryl is generally thought to be more effective than other antihistamines for reducing the itching and inflammation from allergic reactions, such as from bee stings or poisonous plants.

How Antihistamines Work

Antihistamines bind to and block histamine receptors that are found all over the body. This prevents histamine from binding to the receptor, therefore blocking its response and producing the symptoms commonly associated with allergies such as itching and inflammation.

Histamine release is triggered by a variety of things, including:

• Pollen
• Dust
• Pet dander

Although antihistamines work well to reduce the symptoms of allergies after they begin, they are more effective if taken before being exposed to allergens (e.g. pollen).

Final Words

Thanks for your question!