So, Do Lateral Flow Tests Have An Expiry Date?

Another reason why stockpiling lateral flows is not such a good idea.
Have your tests expired?
Emma Farrer via Getty Images
Have your tests expired?

With lateral flow and PCR tests no longer available for free (FYI, they were never free – it was paid for by your taxes), many are worried about accessing Covid testing in the future.

From April 1, LFTs, which were up to now been available via the government website and local pharmacies and community centres, will come at a cost.

Some people have resorted to stockpiling for fear of running out when they really need them in future. But we know that’s not a good idea.

Not only does it deny resources to those who genuinely need it – think care home staff, those visiting the vulnerable, and those with hospital appointments – they could be rendered useless over time.

Most things in life come with an expiry date. And so do lateral flows. While you might be hoarding them, their efficiency can reduce over time.

When do lateral flow tests expire?

The thing to look out for is the liquid that you swirl your swab in before testing.

That’s because this solution can expire. According to NHS England, this buffer solution has a shelf life of two years. But you might notice it losing effectiveness before then – that’s because the amount of liquid can evaporate.

If you’ve kept an old kit for months, you’ll notice that once you go to squirt out the liquid on to the testing device, there aren’t enough drops.

And some kits even come with an earlier expiry date. Some will display dates such as 2022-02, meaning you must use them before February 2022, for example.

How do you know if a test has expired?

You can check the expiry date on your Covid kit box to see when the LFTs may no longer be working. If the buffer solution looks like it’s depleted, it may mean there isn’t enough liquid to show an accurate reading.

Professor Tim Spector, lead scientist on the Zoe Covid Study app, confirms to HuffPost UK: “Lateral flow tests or LFTs do come with an expiry date on the box. However, the date on those can vary widely and we are still unsure how inaccurate they become.”

It’s likely the dates err on the side of caution, Prof Spector adds. “However, an expired test will produce invalid results. If you have a few boxes at home, it would be wise to take a quick look for the date and use them in order of which box runs out first.”

Should you still be doing LFTs?

Once they are no longer free, you might be tempted to use LFTs more sparingly. But Dr Spector still recommends testing at the onset of any cold-like symptoms.

“Early data from 100,000 Zoe Covid Study contributors suggest LFT accuracy remains high,” he says. “The data shows LFTs are almost 80% effective in detecting positive cases and as high as 97% accurate in identifying negative cases.”

LFTs remain a valuable tool for monitoring Covid, he says, and everyone should have a small supply to test themselves when they have cold-like symptoms.

“Also, when cases are so high we would be better to rely on knowing the symptoms and staying at home, as there is a one in five risks of being falsely reassured.”