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Original poster

How quickly for positive to show on LFT?

27 replies

AubergineParmigiana · 27/07/2021 17:35

Just that really.

For those who have had a positive, did it show pretty much straight away?

I'm just sat doing one now, it's negative at 15 minutes. Obviously I'll wait it out and do a final reading at 30 minutes, but just got me wondering m how likely is it that tests that are negative at this point then turn positive at 30?

OP posts:
GrrRightBackAtYou · 27/07/2021 17:51

Oooh good ask op.

I always wonder this as I sit and wait for results.

YouthfulIndiscretion · 27/07/2021 17:52

Good question. We’ve done a bunch of tests in our house but never got a positive so I’m curious how quickly they show up.

DinosaurDiana · 27/07/2021 17:54

I asked this some time back and was told that it pretty much shows up straight away, but you should read it after 30 mins.

PeonyTime · 27/07/2021 17:54

DSs took about 20 mins. It was pretty faint tho. The PCR was positive 6 hrs later.

jumpbounce · 27/07/2021 17:56

I've got 2 very faint positive tests (awaiting PCR results) took around 15-20 minutes to see a hint of a line and then it darkened ever so slightly (more that the test strip dye cleared completely at the 30 minutes and made the line more noticeable at that point)

JustOneMoreStep · 27/07/2021 17:56

For me there was something there really quickly but it wasn't really obviously positive until about 20mins in.

daphnedoo12 · 27/07/2021 18:03

MIL came up really dark within 2 minutes and she was asymptomatic

DM was very sick, lots of symptoms and took a PCR. While waiting 50 hours for results she initially got a negative lft and then a very dark positive that came up within 10 minutes.

DSis got a clear positive after ten minutes too

Scarby9 · 27/07/2021 18:10

Someone I know, working in a school and sent home to self isolate because of a positive case in the class she was in, did her regular biweekly LFT test. She checked it at 5 and 20 mins - negative - and went back at 27 mins to see a very faint line. Confirmed by PCR and very mild symptoms followed.

IsabellesMissingSock · 27/07/2021 18:13

My first positive took bang on 30 mins for a v faint line. I didn't believe it, so did another later that day, which took about 20 mins to produce a paleish line (but definitely a line)

TattyDevine · 28/07/2021 12:27

I worked in a LFT centre and they would always show sooner than 20 minutes but you read the result between 20-30 mins depending on brand (new ones being rolled out for September will be 15 mins).

Anecdotally when my daughter tested positive the line was grabbing on to the dye as it filtered past and just got darker and darker 😆

Was still a very definite line at 20-30 mins and still is as a souvenir for the Covid time vault.

Ours weren't, and we went on to test negative PCR and she was positive so it reflected that. In my experience you don't have the cassette showing white at 15 minutes then suddenly it goes mauve.

TattyDevine · 28/07/2021 12:29

Just saw the other replies and it sounds like there can be some very different experiences but they don't reflect what I've seen. Probably depends on brand, person, and stage in infection. And possibly even variant, who knows...

NoNobramma · 28/07/2021 12:37

My son had a line that disappeared- haven’t a clue if it was a positive or not. It was very strange and I wasn’t alone so it was seen by two of us. Weird!

Begsy · 28/07/2021 13:06

Both my LFT came up positive instantly confirmed the next day with a PCR - I was lucky as it only developed mild symptoms.

wecarryon · 28/07/2021 13:23

Both mine and my friends LF tests showed positive within 2 mins of taking them, mildly symptomatic at that point (obviously did PCR after)
Having done hundreds of negative LF's for work it was quite a shock to see anything different on the test, but it was a clear line fairly quickly

Darbs76 · 28/07/2021 13:47

Ours came up in a few mins

Original poster
AubergineParmigiana · 28/07/2021 14:06

Ooh, interesting!!

Thanks all. I guess we can take from that that if positive, its likely to show up pretty quickly, but not in all instances and especially not early on.

Thanks for all the responses, I've been wondering about it for ages. Thank god no positives in our house...touching wood!!!

OP posts:
CircleofWillis · 28/07/2021 14:07

Mine showed positive as the sample moved up the window. The line was far thicker and darker than the test line.

trying29 · 28/07/2021 14:16

I was really unwell with COVID in MAy and never tested positive on a LFT

x2boys · 28/07/2021 15:14

My son has just tested positive today, very strong positive came up straight away, dh deceided he didnt trust it and tested him again🙄 second one positive but much lighter line, we are just waiting for for a postal PCR test.

GrrRightBackAtYou · 10/08/2021 20:06

@x2boys was PCR positive?

Iknowtheanswer · 10/08/2021 20:09

DH and I had positives that came up as the liquid moved across, so seconds really.

Iknowtheanswer · 10/08/2021 20:10

I kept a photo as a souvenir Grin

How quickly for positive to show on LFT?
lookingsusbro · 10/08/2021 20:14

Mine and ds2's positive lft took 20 minutes to show a faint line, dd's very strong positive came up in 5 minutes.

wineandsunshine · 10/08/2021 20:32

My DS tested positive last week on LFT within ONE minute!

CatAlice · 10/08/2021 21:38

I did one today and it showed up positive within 2 minutes. Awaiting PCR result.

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