You’ve got the sniffles and your nose is running like a tap. The tissues feel like sandpaper.

Many Australians reach for cold and flu tablets, expecting them to “clear the sinuses” and get them through a cold. They often promise fast relief.

But the evidence is clear: for nasal congestion, these medicines do not work as well as they claim. So why are they still being sold?

What’s actually in cold and flu tablets?

Most over-the-counter cold and flu tablets contain a mix of ingredients. Some packs contain different tablets for day and night.

“Day” products often include paracetamol or ibuprofen to ease aches and pains, along with a decongestant for a runny or blocked nose. “Night” products typically have an extra ingredient – an antihistamine to make you drowsy and help with sleep.

In Australia, the most common oral decongestant used in these products is phenylephrine. It works by narrowing blood vessels in the nose, reducing swelling and making it easier to breathe.

You can also buy phenylephrine as a nose spray, although it’s less common. If you spray phenylephrine into your nose it works well as a decongestant. But a large body of research has established it has almost no effect when swallowed in a tablet.

So, why is phenylephrine still widely sold?

Some important context

In the early 2000s, the main decongestant in cold and flu tablets was pseudoephedrine. Phenylephrine was rare as an oral........

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