Naphazoline/pheniramine

Naphazoline/pheniramine, sold under the brand name Naphcon-A among others, is a combination eye drop used to help the symptoms of allergic conjunctivitis such as from hay fever.[1] It contains naphazoline and pheniramine.[1][2] It is used as an eye drop.[2] Use is not recommended for more than three days.[3]

Side effects may include allergic reactions, eye pain, and dilated pupils.[1][4][3] It is unclear if use in pregnancy is safe.[2] Nephazoline works by resulting in constriction of blood vessels thus decreasing redness while pheniramine works by blocking the effects of histamine to stop itching.[2]

The combination was approved for medical use in the United States in 1994.[5][2] It is available over the counter.[5][1] In 2017, it was the 203rd most commonly prescribed medication in the United States, with more than two million prescriptions.[6][7]

Medical use

It is administered topically with one to two drops applied to the affected eye(s) up to four times daily.[1]

Adverse effects

• Pupils may become enlarged temporarily
• Overuse may cause more redness
• Those with heart disease, high blood pressure, narrow angle glaucoma or who have urination trouble are discouraged from using the product
• It is recommended to remove contact lenses before use. Use with contact lenses can lead to reduced oxygenation of the underlying cornea
• If infants or children accidentally ingest the drops, it may lead to coma and significant reduction in body temperature. If such ingestion occurs, immediately calling a poison control center is recommended[1]