Please select the country or location you would like to see content from.
country picker icon
treatment icon


Benadryl Plus

Written by Healthwords's team of doctors and pharmacists based in UK | Updated: 14.02.2023 | 2 min read

Benadryl is the brand name for a line of over-the-counter products used to manage allergies. These products contain the antihistamine diphenhydramine. Benadryl Plus (also known by the full name Benadryl Allergy + Congestion) is a product that contains the hay fever medication diphenhydramine with the decongestant medication phenylephrine. This product is formulated as a tablet and oral liquid, the only Benadryl product that combines an antihistamine with a decongestant.

Who should take the medication?

Antihistamines can help relieve allergy symptoms, such as a runny nose, sneezing, itchy and watery eyes, and an itchy nose or throat. They work well for hay fever, pet allergies, and dust allergies. If you are also experiencing nasal congestion due to your allergic condition, a combined product with a decongestant can help relieve that stuffy blocked-up feeling.

How does it work?

During an allergic reaction, your immune system releases a chemical called histamine, responsible for bothersome symptoms. Antihistamines stop histamine binding to its target sites in your body, reducing the immune response and symptoms.

Phenylephrine helps relieve nasal congestion, which can occur due to allergies. Nasal congestion is caused by swelling (inflammation) of blood vessels in your nose. Phenylephrine is a vasoconstrictor that narrows the blood vessels in your nose. This leads to a reduction in the swelling, leading to an improvement in breathing through your nose.

Should anyone avoid taking it?

Like all medications, don’t take it if you previously had an allergic reaction to the medication, if you have severe kidney or liver problems, or if you have other medications or medical conditions that you would normally discuss it with your doctor or pharmacist before starting something new. Do not take it if you have breathing problems, glaucoma, or an enlarged prostate. You should also ensure you do not take a combined antihistamine and decongestant product alongside another antihistamine or decongestant medication.

Are there any side-effects?

As with all medications, some people may experience side effects. All antihistamines have the potential to cause drowsiness, even antihistamines that are classed as non-drowsy.

Potential side effects from decongestants like phenylephrine can include nausea, vomiting, headache, dry mouth, restlessness, anxiety, and difficulty sleeping. Occasionally, some people may develop fast or irregular heartbeats. You should stop using the medication and seek medical advice if this happens.

Was this helpful?

Was this helpful?

Newsletter icon
Subscribe to our Newsletter
to get monthly notified about our latest health and wellness topics.
By clicking Subscribe, I agree to the Healthwords Terms & Conditions and Privacy Policy and understand that I may opt out of the newsletter subscription at any time.