Positive LFT after 30 minutes

[FallenSky]

DS took a lateral flow test this morning before school. Set the timer for 30 minutes, checked and it was negative. I've just got home and gone to throw it away and it now has a line on the T line. It says not to read after 30 minutes but I've no way of knowing whether the line came at 31 minutes or 4 hours later iyswim. Is this a known thing? Wondering whether I should get him to do another LFT when he's home or try to book at PCR or just take the negative result at 30 minutes as the proper result. We've all been doing the LFTs for weeks now and this is the first time any of them have had a second line even hours later.

The guidance says that you may get false positives if reading after 30 minutes so I would probably ignore it. If I was worried, I might get my DC to take another test tonight/tomorrow morning?

Test again and read it within the 30 minutes. Take that as the real result.

Thanks, good to know that it can have a false positive if left. I think I'll get him to do another one just to be on the safe side though.

Oh I wondered why they said set a timer. I just wandered back to look at mine after 30 ish minutes. Interesting. Yes do another tonight.

He's just done another so will hopefully know either way in 30 minutes.

@FallenSky what was the result of the second test?

there was a thread like this the other day. It's not that uncommon. If it didn't show within 30 minutes I wouldn't worry but would prob do another one to be sure.

...and??

Did similar with one of my sons a few weeks back, definitely negative at 30 mins, but v faint line on T at 50 mins. Think this does happen as the leaflet says to disregard any results after 30 mins

See, pregnancy tests say this but early squinters can take a while to show, and don’t happen if you’re not up the duff...

Always follow instruction. Results are only valid during that time frame. Everything else should be ignored. The BMJ covers false positives so please ignore it.

Sorry.... Second LFT was negative at 30 minutes, took that as the result but kept the test to see if the same thing happened. Still no second line now so feel confident this morning was a false positive.

Good news then