Why Are Some Cold Medicines So Useless at Relieving Nasal Congestion?

Millions of Americans regularly turn to over-the-counter remedies to alleviate the symptoms of a stuffy nose. However, it might be time to look elsewhere. In September 2023, a U.S. Food and Drug Administration (FDA) advisory panel unanimously agreed that phenylephrine, a decongestant in many cold medicines, is no more effective than a placebo when taken orally.

As the most popular store-bought decongestant in the United States, phenylephrine is included in various cold and allergy remedies such as Sudafed, DayQuil, and Benadryl. The effectiveness of this drug has been in serious doubt since 2007, when University of Florida researchers first petitioned the FDA to review its usefulness and examine whether phenylephrine products should remain on store shelves. Since then, three major studies have found that phenylephrine is no more effective than a placebo in treating nasal congestion, as almost none of it enters the bloodstream when taken orally, as opposed to via a nasal spray.

Phenylephrine began gaining popularity around 2005, when decongestant medicines containing the active ingredient pseudoephedrine were moved behind pharmacy counters to halt their use in the illegal production of methamphetamine.

While medicines containing pseudoephedrine are still available and don’t require a prescription, their purchase now involves a relatively time-consuming process. They must be dispensed by a pharmacist, with a limit on the quantity a single customer can buy. As a result, the over-the-counter alternative phenylephrine has become the go-to decongestant. In 2022, 242 million phenylephrine products were sold in the United States, totaling $1.76 billion.

Now, the FDA must decide whether phenylephrine should have its designation as “generally recognized as safe and effective” removed. While the safety of taking phenylephrine at recommended doses is not in question, the research strongly suggests that it should not be described as “effective.” Recent findings indicate that when taken orally, phenylephrine metabolizes too quickly for it to be effective, with only traces of the ingredient (approximately 1%) reaching the nasal passages, where it is meant to constrict blood vessels.

If the “safe and effective” designation is revoked, drugmakers may need to withdraw phenylephrine products from store shelves or reformulate their products. However, phenylephrine is still considered effective when applied nasally, so nasal sprays and drops containing phenylephrine are not under review.

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