Answer: Both of those products contain antihistamines, which treat allergy symptoms.

They might also shed light on the familiar sleep-inducing effects of cold and allergy medications that contain antihistamines, the researchers said.

But avoid using topical products that contain antihistamines; they can make the reaction worse by causing a sensitivity reaction.

Allergy and cold products also contain dextromethorphan, antihistamines, and expectorants.

Avoid decongestant medicines that contain antihistamines unless your doctor specifically recommends them.

For itchy eyes, there are saline washes and prescription drops containing antihistamines.

However, if you're taking other drugs that also contain antihistamines - like cold or allergy medications - you could inadvertently take too much.

The drops usually contain antihistamines and decongestants that help calm eye allergies.

Since both contain antihistamines, it is not recommended to use them at the same time.

These drugs contain antihistamines - typically, diphenhydramine, which can be sedating.