How many days after faint positive should i test again

I know how hard it can be sometimes to tell if it's a line or not. When I was trying to conceive, I remember squinting at pregnancy tests trying to work out if there was a faint line or not. In fact, I always asked my husband to check – and then I admit I may have sometimes done a repeat test to be sure!

Why is the line so faint?

If the line is faint, then it is likely that you are testing very early on in your pregnancy.

A pregnancy test is designed to show a line if it detects, in the urine you dipped it into, a threshold level of a hormone called human chorionic gonadotrophin (hCG). Levels of hCG rise rapidly in the early weeks of pregnancy, are at their highest at about 10 weeks of pregnancy, and then slowly fall again.

But if you're taking the test very early on in your pregnancy, your levels of hCG will be small, meaning that, although there is enough for be detected by the test kit, it is only enough to create a faint line.

Can a faint line ever mean I'm not pregnant?

A false positive pregnancy test is extremely rare ("false positive" means the test is positive but you are not actually pregnant). That's assuming, of course, that you haven't used a test that's past its expiry date or are 'reading' the result long after the wait time outlined on the packet.

A false positive can occur if you are on particular medication, such as a fertility drug containing hCG, or if you have a medical condition, such as an ovarian cyst, which can raise your hCG levels. A pregnancy test may also be falsely positive if you have recently had a miscarriage or termination of pregnancy, as it takes a little time for the hCG levels to fall.

It is also possible that you can have a genuinely positive pregnancy test and then, a few days later, if you test again, it's negative. This is because urine home pregnancy tests are extremely sensitive and can pick up a pregnancy in the very early stages – and, unfortunately, not all pregnancies progress past these very early stages. If the pregnancy doesn't progress, then a new test will show as negative. This is called a chemical pregnancy – or a very early miscarriage – as it tends to occur before a heartbeat can be seen on the scan, so before approximately 5 or 6 weeks of pregnancy. In this situation, bleeding tends to start soon afterwards but, if it does not, then please see your doctor.

So if I get a faint line, should I do another test?

Yes, that's what I'd recommend – but leave it a couple of days or so. Levels of hCG double every 48 to 72 hours in the 1st weeks of pregnancy so the line on the pregnancy test may be stronger when you test in a few days' time.

I'd also recommend that you make sure you do the pregnancy test the first time you wee that day as that's the time of day when your wee is likely to be more concentrated.

What's hCG exactly – and how do pregnancy tests work?

HCG is a hormone that's made initially by the embryo itself, and then by your placenta, and has various roles, from supporting the corpus luteum (what is left when the egg is released) to supporting implantation.

The pregnancy test works by absorbing your urine onto the pad or strip of the pregnancy test and, if there's hCG present in that urine, it will bind to antibodies which are attached to the coloured dye in the test that forms the blue or pink test line – and make that line show up. If there is no HCG present in your urine, and you are not pregnant, there are no antibodies to bind to the dye, so no line forms.

There is generally a control line in a pregnancy test to check that the test is working. In a positive pregnancy test, both the test line and the control line should be seen.

About our expert Dr Philippa Kaye

Dr Philippa Kaye works as a GP in both NHS and private practice. She attended Downing College, Cambridge, then took medical studies at Guy’s, King’s and St Thomas’s medical schools in London, training in paediatrics, gynaecology, care of the elderly, acute medicine, psychiatry and general practice. Dr Philippa has also written a number of books, including ones on child health, diabetes in childhood and adolescence. She is a mum of 3.

Pics: taken from the MadeForMums Chat forum

Read more

• Early signs and symptoms of pregnancy
• What is chemical pregnancy?
• I'm pregnant, what should I do next?

The FDA recommends to take at least two COVID-19 antigen tests 48 hours apart before ruling out a possible infection. Justin Paget/Getty Images hide caption

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The FDA recommends to take at least two COVID-19 antigen tests 48 hours apart before ruling out a possible infection.

Justin Paget/Getty Images

We regularly answer frequently asked questions about life during the coronavirus crisis. If you have a question you'd like us to consider for a future post, email us at with the subject line: "Weekly Coronavirus Questions." See an archive of our FAQs here.

Ah, the start of a new school year. Maybe you're one of millions of Americans who have started mingling with peers in the dorms and suddenly find yourself sniffling and wondering if you have COVID-19.

Or you're just getting back from your summer vacation and the back of your throat has a worrisome itch.

You consider taking an at-home rapid test, but you have lots of questions. With new FDA recommendations on testing, how many times should you test for a definitive result?And, how infectious are you if the positive line is faint? And what if the test turns positive — but only after an hour?

We posed your questions to the experts: Dr. Abraar Karan, infectious disease researcher at Stanford; Meriem Bekliz, virologist at the University of Geneva; and Dr. Preeti Malani, professor of medicine at the University of Michigan. Here's the scoop:

So I caught COVID-19 and after 10 days I'm still testing positive. But the line on my rapid test is really faint now compared to a week ago. What's the deal? Exactly how contagious am I?

"The faintness or darkness of the line probably has some correlation to degree of infectiousness especially early on [during the infection]," says Karan.

So if the line is faint, that could mean your risk of accidentally passing the virus on to others is low.

"Some people may not be infectious because the tests could be picking up viral debris from a waning infection," says Bekliz.

But don't rip off your mask just yet: There could be other reasons for a faint line.

There is "some room for error" with those rapid tests, Karan says. You're sticking a cotton swab up your nose and hoping to snare some virus. A faint line could mean you've collected less virus this time around. Maybe you swabbed for less time or in only one nostril when your test instructions say to swab both.

"In general, a darker line is a result of more virus [on the swab]," says Malani. "But antigen tests are not especially sensitive, so even with a negative test, you can be contagious."

Sothe bottom line, say our experts: If you're testing positive – even with a faint line — you should behave as if you are contagious.

If there's any hint of a positive line, Bekliz recommends you continue to wear a mask, work from home if possible and generally limit contact with other people.

Last week I tested positive for COVID-19 and went through the recommended 5 days of isolation and additional 5 days of masking. How many times do I need to test negative before it's OK to assume I'm virus-free?

Figuring out when it's OK to ease up on your safety measures after catching COVID-19 can be tricky.

If you suspect that you may have COVID but haven't tested positive yet, the FDA now recommends serial testing, which means you should repeat your home test after 48 hours to make sure you aren't accidentally getting a false negative test.

And what should you do if you already tested positive and want to know when you're finally negative?

"The recommendations for serial testing are for people that have been exposed and are trying to diagnose themselves," says Karan. "They're saying to repeat the test after a day or two, but not if your first test is already positive and you're testing to become negative."

Once you have tested positive and your body starts clearing the virus, a negative rapid test should be a pretty good indication you're no longer infectious, so long as youfollow the test protocols correctly and wait an appropriate amount of timebefore testing.

"If it's been like five days [since the onset of symptoms], and the test is negative, then I would feel good about that," says Karan. "If the test is negative one or two days after symptoms start, then I would maybe think you didn't get a good sample and should test again."

While that's reassuring, there wasn't agreement among our experts about exactly what to do. While Karan says one negative test after an appropriate amount of time is good enough, Malani says you should take two just to be sure.

"Usually you want a couple negative tests," says Malani. "If you have two negative antigen tests, that's really helpful."

So that first negative test is likely a good sign, but taking an additional test 24 hours later is a great way to confirm the result and rule out errors in testing.

I was feeling a bit off and took a COVID-19 test. After 15 minutes it looked like the test was negative. But when I came back to check the test an hour later a positive line had appeared! Then I retested three times and they all came back negative. Does this mean I could have COVID-19?

This is a pretty unusual circumstance, our experts say, but one that could potentially indicate bad news.

"The tests aren't really meant to be read an hour later," says Malani. "But it would be a little bit concerning for someone who has symptoms and has their test turn positive later."

Each test kit has its own recommended timeframe for reading the test. BinaxNOW and iHealth kits say you should read the test after 15 minutes, but not after 30 minutes. INDICAID test kits say you should read the test after 20 minutes, but not after 25 minutes. Reading the test after the recommended time frame could lead to a false positive.

However, Karan agrees that "it would be less likely to be a false positive if someone's having symptoms and we're at a time when there's a high amount of virus being spread."

Following the FDA recommendation to test at least twice andwaiting 48 hours between testscan help determine your true COVID-19 status as well.

"My advice would be to probably stay put and not expose anyone, and then perhaps repeat the test," Malani says. "Now, if you're feeling great the next day and your test is negative, maybe it was nothing."

Or simply "assume you're positive if you have symptoms," Karan says. "Try to get a PCR test and retest again [at home] in the next few days. If the PCR test is negative, you're probably OK."

No matter the circumstances, if you're worried that you could have COVID-19, our experts think your best bet is to repeat your at-home test over a couple of days. So if you want to ace COVID Testing 101 this school year, just remember that two negative tests are better than one.

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