You're not imagining it, over-the-counter cold and flu tablets probably don't work

Here's the low-down

Most over-the-counter cold and flu tablets contain a mix of paracetamol and phenylephrine. Image: Getty

Get out your driver’s licence, because your noses are going to need it this flu season if you're battling with serious congestion. 

It’s a tale as old as influenza. Shivering and snotty on the couch, you know you’re coming down with the lurgy, and in an act of heroism, your partner offers to pick you up some Butter Menthols and cold and flu tablets from the pharmacy. They return, arms laden with supplies to see you through a day or two of bingeing Yellowjackets, at which point you spy the tablets they’ve procured: over-the-counter cold and flu.

“Did you get the ones with pseudoephedrine in them?” you ask trepidatiously, a warning in your husky voice.

“Uh… no, but the pharmacist told me these were just as good,” comes the nervous reply.

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“Did you have to show your driver’s licence for them?” 

But you already know the answer. Because everyone who has ever had more than a middling head cold will tell you the same thing: if you’re not made to feel like a speed-dealing criminal by being asked for ID when purchasing cold medication, you may as well be popping Skittles, for all the good it’s going to do your clogged sinuses. 

The evidence is in: phenylephrine doesn’t help with congestion

Most over-the-counter cold and flu tablets contain a mix of paracetamol and phenylephrine, the latter included as a decongestant to help with clogged-up noses and sinuses. It’s supposed to act to narrow blood vessels in your nose to provide relief, in place of its pharmaceutical second-cousin-once-removed, pseudoephedrine. 

The problem is, several studies have found that because of the way phenylephrine is metabolised (through the gut and liver), it doesn’t enter the bloodstream in large enough amounts to provide any decongestant benefit. 

US pharmaceutical manufacturer Schering-Plough funded a 2006 study that found phenylephrine was “not significantly different from placebo”, while in 2015, researchers in Florida filed a citizen’s petition to the American FDA calling for oral phenylephrine to stop being marketed as a decongestant. When that failed, this 2022 paper’s title asked the pertinent question: Why Is Oral Phenylephrine on the Market After Compelling Evidence of Its Ineffectiveness as a Decongestant?

Phenylephrine has a long history of use in cough and cold medicines. Image: Getty

Pseudoephedrine vs Phenylephrine

Pseudoephedrine - the drug in those behind-the-counter cold and flu medications you usually need to show your driver’s licence to purchase - is considered an effective decongestant. But, as a human with two nostrils and an immune system, you probably already knew that. 

The problem is, pseudoephedrine is considered an “illicit drug precursor”, meaning it can be used to manufacture hardcore amphetamines such as meth and speed. In order to stop the process of ‘pseudo-running’ - whereby criminal enterprises would employ people to buy up large quantities of the drug from multiple pharmacies to be illegally cooked up into street drugs, the Project STOP database was created.

An initiative of The Pharmacy Guild of Australia, the database allows chemist shops to opt-in to the system (although some made the decision to stop selling pseudoephedrine products altogether) by logging the identification details of anyone buying them. The database then identifies unusually high purchase frequency to allow authorities to crack down on pseudo-runners.

Pseudoephedrine is considered an effective decongestant. Image: Unsplash

Why is phenylephrine still being marketed as a decongestant?

Efforts abroad to change the way phenylephrine is marketed have been met with resistance, with the FDA in the States claiming the issue required further investigation, according to The Wall Street Journal. 

The TGA stands by the product, claiming phenylephrine has a long history of use in cough and cold medicines in Australia.

“Its safety and efficacy are documented in standard reference texts,” a spokesperson told Body+Soul. 

“However, the perceived effectiveness of medications indicated to relieve symptoms such as nasal congestion can vary between individuals. Additionally, pseudoephedrine and phenylephrine have differences in the way they work which may result in some differences in their effectiveness.”

“Legislation requires that the active ingredient(s) is displayed prominently on the main label of the medicine to enable consumers to make informed choices when purchasing over-the-counter medicines.” 

But with Covid cases on the rise just as this year’s flu season - pipped to be severe - is sinking its teeth in, what’s an under-the-weather citizen who wants fast relief to do? Apart from making sure your flu shot is up to date, it might be worth keeping that driver’s licence nice and handy, as you spare a thought for our Kiwi brothers and sisters, who require a doctor’s prescription just to get their hands on a pack.

Originally published as You're not imagining it, over-the-counter cold and flu tablets probably don't work