Home Tips and Tricks How To Help Avoid Getting A False Positive On TSA Swab Tests

How To Help Avoid Getting A False Positive On TSA Swab Tests

by SharonKurheg

If you’re traveling by plane in the United States, you know that sometimes you’ll get pulled aside for a “swab test.” Being a “chosen one” appears to be random (although some think it’s if you look suspicious or if a TSA officer still has to fill his/her quota for the day) and it’s certainly harmless enough – they swab your hands (and/or your laptop, shoes, film, cell phone, bags, wheelchair or cast) with a cotton cloth and check for explosive residue in an Explosives Trace Detector (ETD). If you’re negative, you’re free to go. But if you’re positive, you have to go to the next step of security.

The problem is, some people wind up with a false positive. Here’s why:



See, the test is looking for the stuff bombs are made of and the two chemical compounds that are usually used are nitrates and glycerin.  The thing is, there are a lot of typical, everyday things that have those chemicals in them:

  • hand soaps that contain glycerin
  • lotions that contain glycerin
  • cosmetics, hair products, etc. which may contain glycerin
  • baby wipes which may contain glycerin
  • certain medications (e.g., nitroglycerin and other nitrates)
  • lawn fertilizers
  • munitions
  • accelerants
  • fireworks and other pyrotechnics

So what can you do? Simple. Before you get to X-ray, wash your hands….REALLY well (don’t forget to scrub your cuticles and under your fingernails!). Make sure there are no remnants of soap or lotion (or meds or munitions or fireworks) on them. If you recently used a baby wipe, again, make sure your hands have been washed afterwards (although really, if you’re using a baby wipe for its intended use, I hope you’re washing your hands anyway, if you catch my drift). Same thing with your shoes, and if your suitcase or laptop or anything else may have somehow come in contact with any of those chemicals, wipe them down too.

If you still get flagged as positive, don’t make a fuss – most likely you’re going to get patted down again by a TSA worker of the same gender as you, and if you want to get on that plane of yours, there’s nothing you can do about it. If you become belligerent or hostile, they’re just going to think you have something to hide and it certainly won’t get you through the process any faster. So let them do their job and if you have nothing to hide, you should be done soon enough anyway. Assuming you got to the airport far enough in advance (you did get to the airport far enough in advance, right?), the chances of you missing your plane because of this short delay are pretty small.

By the way, if you’re aware of any contact you may have had with those chemicals, let the TSA workers know…it might help them get to the bottom of things faster so you can be on your merry way.

By the way, you can probably thank, in part, the would-be bomber of the Dec. 25, 2009 Northwest Airlines flight 253 over Detroit for prompting the whole hand-swabbing thing. The year after that, TSA implemented the program and spent about $60 million on ETD machines. They’ll never admit that’s why the hand swabbing all started but really, c’mon, what else could it be? So thanks, bomb failure dude!

A tip of the hat and a huge THANK-YOU to Shannon D., who gave us the initial heads up about this topic!

Feature Photo: TSA

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This post first appeared on Your Mileage May Vary



Kelly MacKay January 30, 2018 - 8:36 am

I haven’t flown to the US in many years but I have never heard nor experienced this TSA test, I ve walked through metal detectors, and had wand waved over me. I’ll have to look it up. Is this only done in the USA?

SharonKurheg January 30, 2018 - 9:41 am

Hi Kelly! I can’t speak for other countries (we travel quite a bit but only travel internationally once every other year or so) but the TSA has been doing it since at least 2010, if not before then. Not everyone get swabbed (unlike going through the metal detector, which just about everyone does, or the wand, which happens relatively frequently) and I think it’s only happened to me a small handful of times. So I could see how you might not have experienced it. 🙂

Kelly MacKay January 30, 2018 - 10:24 am


Tony October 18, 2020 - 10:53 pm

they’ve done this plenty of times to me in australia and sometimes hong kong. Its always random, which is why i think its silly. if you want to test someone for explosives, why leave it to random chance? And even if you test positive, theres so many plausible reasons that its a moot point if security doesn’t find anything on u.

Mfb123 April 29, 2019 - 2:39 pm

I’ve had two false positives…once on my shoes, once on my laptop. To this day, I have no idea what triggered it.

SharonKurheg April 29, 2019 - 10:40 pm

They swabbed my hands once. I’m guessing hand lotion? But I ddin’t know better then. I sure do now! 😉

V April 30, 2019 - 12:35 am

Thanks for giving the bad guys a heads up for getting away with anything bad planned😕

SharonKurheg April 30, 2019 - 12:43 am

I’m sure the bad guys already know. After all, all it takes is a simple Google search to find out that kind of info. The stuff TSA really doesn’t want us to know because it’s a sign of a security risk, we don’t know 😉

YULtide May 4, 2019 - 7:59 pm

I got a false positive once at LHR and after I had been cleared the agent told me that recently polished shoes can cause a false positive.

SharonKurheg May 4, 2019 - 9:08 pm

Wow, never heard of that one!

Glenda Collier August 27, 2019 - 12:34 am

I had a stopover in Iceland to return to the U.S. I was “randomly” chosen for security with an ssss written on my boarding pass. I’m 67 age, a past teacher, not criminal record. I received a swab “test” on my hands, my stomach and above my socks on both feet. I’ve felt sick ever since. What is the liquid the TSA puts on the cloth for the swab test. Bye the way, I use glycerine soap, that’s probably all it was. People in there with a baby, probably glycerin from the baby wipes, a young female college student. All of these terrorist looking people.

SharonKurheg August 27, 2019 - 12:52 am

You kind of lost me on your last sentence – “All of these terrorist looking people.” Anyone could potentially be a terrorist, regardless of what they look like, no?

CHRIS October 18, 2020 - 8:24 pm

You think TSA puts a liquid on the swabs to make people sick? What’s your opinion of the AIT?…..perhaps a mind-control device?

Jennifer K Lovett May 25, 2021 - 11:57 am

I have been stopped both times I was swabbed. I use wooden matches. Could that be my problem?? The person both times was really cranky about the whole thing. I did not have any problem, just wished I knew what I could have touched. She didnt care to tell me.

sunkissedpeach386 June 13, 2021 - 3:35 pm

My boyfriend just got flagged on a return trip – he had just used hand sanitizer (of which glycerin is a main ingredient along with alcohol). Why are they bothering to test for this now with COVID-19 and so many false positives?????

SharonKurheg June 13, 2021 - 3:43 pm

No idea. But I suspect because, despite all the false positives, they’ll also still occasionally find someone who has residue of bomb materials on their hands or possessions.


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