Skip to Content, Navigation, or Footer.
The Tufts Daily
Where you read it first | Sunday, December 10, 2023

Phenylephrine: The decongestant that leaves you stuffy

The main ingredient in many decongestants is under review for its lack of effectiveness when taken orally.


Cough medicine is pictured.

Going into winter, your cold medicines could end up looking a little different based on a forthcoming decision from the FDA. Phenylephrine is an over-the-counter decongestant in many different medicines, including Dayquil Cold and Flu Relief, Sudafed PE and Benadryl Allergy Plus Congestion. But an FDA advisory board recently concluded that at current dosages, oral phenylephrine is not effective.

The independent advisory committee, assembled by the FDA, will now review the findings and determine whether phenylephrine is effective. If they come to the same conclusion that the committee did — which they often do — there would be a process to remove medications with phenylephrine from the shelves, and medications containing phenylephrine, especially those containing multiple active ingredients, such as Dayquil, would need to be reformulated. CVS has already announced that it will stop selling products containing oral phenylephrine.

Phenylephrine is ineffective due to filtration which naturally occurs during digestion. When a drug is delivered in pill form, also called oral delivery, it must travel through many harsh environments to make it to the bloodstream. The drug first has to make it through the stomach, which is very acidic and can break down many proteins. The drug then enters the intestines, where the drugs can be degraded while being absorbed into the bloodstream through the intestinal wall. The blood from the intestines travels to the liver, which filters the blood and has proteins that can break down drugs.  

The drugs that can avoid getting filtered by the liver can then circulate the body via the bloodstream. Some of this blood will go to the nose, where the phenylephrine is adsorbed and causes the blood vessels to constrict, reducing congestion. The issue with phenylephrine is that almost all of the drug is inactivated in the intestines and the liver, so not enough phenylephrine can make it to the nose to have a significant impact.

Even though phenylephrine may be taken off the shelves for good, there are still other decongestants available. Phenylephrine can also be delivered in nasal sprays, and any FDA ruling that could prevent oral delivery of phenylephrine would not impact the nasal sprays.  Another popular oral decongestant is pseudoephedrine, the active ingredient in Sudafed.  However, it is not available without a prescription. While cold medicine could end up looking a little bit different in the future, it’s going to be more effective, which is the important part.