Phenylephrine is a drug commonly used in nasal inhalers and nasal drops to combat a blocked or stuffy nose. Thus it is found in many remedies for allergies (such as hayfever), the common cold and sinus problems. In most countries, it is available without prescription in over-the-counter products.
Phenylephrine is a mild stimulant and a vasoconstrictor. It increases blood pressure and also increases the resistance to blood flow through the body, meaning that the heart must do more work. When used as a nasal decongestant, it works by shrinking blood vessels in the nose and sinuses, which reduces swelling and clears airways.
It is sometimes used to treat hypotension (low blood pressure), for instance in cases of shock or while under anaesthesia. An injection of phenylephrine can be used to combat priapism, an excessively prolonged erection. Another common use is in ophthalmic products. In eye drops, it is used to enlarge the pupils before eye examinations and eye surgery, and to reduce redness caused by minor irritations (smoke, dust, allergy, etc). Phenylephrine may also be used in the eyes to treat eye conditions such as conjunctivitis.
According to MEDLINE, side-effects are typically minor. For nasal products, these include a possible worsening of a stuffed or runny nose. In eye drops, the main side-effect is an increased sensitivity to light caused by dilation of the pupils. This presents a risk of damage from the sun's UV rays. In a few cases it also causes eye irritation.
Large doses in any form can cause a fast or irregular heartbeat, headaches, dizziness, sweating, nervousness, paleness, trembling and sleep problems. For this reason, medical advice should be sought if anyone with high blood pressure or heart problems is considering taking the drug.
Phenylephrine is banned in some sports because of its stimulant properties.
Most information taken from:
- MEDLINEplus, "Phenylephrine (Nasal)", 8 January 2003, http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202460.html (23 January 2003).
- MEDLINEplus, "Phenylephrine (Ophthalmic)", 8 January 2003, http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202461.html (23 January 2003).
- First DataBank, "Phenylephrine - Injection", Personal MD, 2000, http://www.personalmd.com/drgdb/304.htm (23 January 2003).
- "Promethazine HCl and Phenylephrine HCl", RxList, 31 December 2002, http://www.rxlist.com/cgi/generic3/promphen_cp.htm (23 January 2003).
Disclaimer: the advice presented above is believed to come from reputable sources. However, it is not guaranteed to be correct, and is no substitute for expert medical guidance. You should consult your physician or pharmacist before taking a medicine, especially if you have an existing medical condition, are pregnant, or are taking other medications. Neither the author nor Everything 2 can take any responsibility for any damage or ill-effects caused as a result of the information in this write-up.