Benadryl is pretty much the only non-expensive thing that works for my horrible nasal allergies. I don't actually TAKE it because it makes me so drowsy i can't. Medically reviewed by C. Fookes, BPharm Last updated on Nov 13, Do not drive or operate machinery if Benadryl makes you drowsy or affects your Ensure you maintain good oral hygiene if you are taking Benadryl long-term. Jan 19, Like most drugs, with Benadryl it is hard to predict effects for an individual person. up after taking non-drowsy Benadryl, and if so, how long does this fog last?. When used over time, Benadryl llng to work to relieve symptoms llong hay fever or allergies, runny pneumonia asthma, hives, and other conditions. Benadryl and Zyrtec are both brand-name over-the-counter products. Gray, S. However, it's not usually a first-choice treatment for treating hay fever or other respiratory allergies. One form of Unisom contains a different ingredient, doxylamine. Benadryl overdose treatment. Allegra is approved for decreasing symptoms of hay fever click here other respiratory allergies, and itchy skin caused by hives, insect bites, and other causes. However, Benadryl isn't usually a first-choice for these conditions because of the risk of side effects such as sleepiness. It works by blocking histamine, a chemical produced by the central nervous system that not only produces allergy symptoms, but plays a role in wakefulness hence the insta-drowsy feeling after you pop a Benadryl. Although some people take Benadryl to treat cough, an analysis of clinical studies shows that antihistamines such as Benadryl don't improve symptoms of cough. Take subsequent doses before meals or at bedtime for the duration of the exposure. After oral administration, the onset of action is approximately 15 to 30 minutes. Drinking alcohol with Benadryl can increase the effects of alcohol and cause excess sleepiness that can impair your abilities. Do not take more than is recommended. Examples of these medications include:. Antihistamine also known as diphenhydramine is the secret ingredient in dose OTC products commonly used for insomnia, including Benadryl, said Alex Benadeyla California-based dual board-certified psychiatrist and sleep medicine specialist. Ensure you maintain good oral hygiene if you are taking Benadryl long-term. Zoloft sertraline is an antidepressant that can cause sleepiness in some people who take it. Hasnain, M. Over-the-counter Benadryl products aren't approved and don't work to treat heat rash. Subscribe to our newsletters. Your doctor can also recommend the most appropriate dosage of Benadryl if treatment with the drug is needed. For children ages 6 to 12 years, the maximum is mg each day. Back To Top. These effects don't decrease with continued use of the product.