By Karim Hammam
Many Australians turn to over-the-counter cold and flu tablets for relief from nasal congestion, but recent research indicates the common oral decongestant phenylephrine works no better than a placebo when swallowed.
What Cold and Flu Tablets Contain
Most cold and flu products combine pain relievers such as paracetamol or ibuprofen with a decongestant for a runny or blocked nose. Daytime formulations typically include phenylephrine, while nighttime versions add an antihistamine to aid sleep. Phenylephrine is also available as a nasal spray, which is effective, but the oral tablet form has come under scrutiny.
Why Phenylephrine Replaced Pseudoephedrine
In the early 2000s, pseudoephedrine was the primary oral decongestant. However, a surge in illicit amphetamine production between 1996 and 2005 led to pharmacy break-ins and armed robberies targeting pseudoephedrine. Authorities tightened restrictions in 2006, reclassifying it as a pharmacist-only medicine. Phenylephrine became the main substitute because it posed less risk of misuse, not because it was more effective.
Evidence Shows Oral Phenylephrine Ineffective
Early reviews suggested phenylephrine was a viable alternative, but newer, higher-quality studies have consistently found that oral phenylephrine does not meaningfully relieve nasal congestion compared with a placebo. The evidence now indicates that swallowing phenylephrine tablets provides no significant decongestant benefit.
Common Cold Symptoms
Typical cold symptoms include a blocked or runny nose, sneezing, sore throat, hoarse voice, cough, fatigue, and feeling unwell. Some people may also experience fever, muscle aches, loss of taste or smell, and pressure in the ears and face.
