Does Flexeril Show Up On A Drug Test: How Can You Avoid Getting Caught

Jordan Barnett | Masters in Chemical Engineering
Jordan Barnett | Masters in Chemical Engineering

Over 15 years of experience dodging drug tests.

Does Flexeril Show Up On A Drug Test?

Yes, Flexeril can show up on a drug test!

For your usual 3-to-5 panel drug tests, Flexeril (also known as cyclobenzaprine) will pass without a trace. But if you go towards the 10, 12, or any laboratory-grade urine drug test, then there’s a good chance you’ll get flagged for it.

And while using this drug is far from illegal, there are cases where taking it can cost you your career. In this article, we’ll talk about two key methods that can help you pass a drug test for Flexeril.

white tablets in a bowl

What Is Flexeril?

Flexeril is a muscle relaxant. Its main ingredient is cyclobenzaprine, which is one of the most effective muscle relaxants on the market right now. It’s used to treat muscle spasms and works as short-term pain relief from physical exertion.

The Drug Enforcement Administration (or DEA) reports that doctors wrote over 25 million prescriptions for cyclobenzaprine in 2011 alone for people dealing with back pain, fibromyalgia, and other related conditions. It’s a generic drug in other countries, but most Americans take it as the prescription drug Flexeril.

It’s mostly used by people between the ages of 18 to 35. Doctors don’t prescribe it to older people because of the danger of side effects and the strength of the drug itself. It works by calming down your central nervous system during muscle spasms, which can lessen your chances of injury or discomfort.

How Long Does Flexeril Stay In Your System?

Since most doctors prescribe Flexeril for about ten days, the drug doesn’t actually stay for long compared to other medications. However, cyclobenzaprine is a powerful drug. While the effects itself will only last for three to five hours, the actual traces of the drug can linger around for much longer – up to two weeks.

Four major factors determine how long Flexeril stays in your body:


Most doctors will prescribe about 5 mg of cyclobenzaprine for people who are using it for the first time. However, for people who need it as maintenance medication, the dosage can be increased to 10 mg. While this means that Flexeril will have a more potent effect on your system, this also means that there’s a lot more of it that your body needs to process.

Body Weight

Closely tied to your dosage is your body weight. If you weigh below 200 pounds. They are more likely to give you lower doses of cyclobenzaprine since it can overwhelm your body in large amounts. If you are above 200 pounds, you need more of the drug to affect your body, and that makes it difficult to remove.

Other drugs

For more serious conditions, you can sometimes take Flexeril with drugs like Tylenol or Zyrtec. While the effects of these drugs are far from fatal, they are noticeable enough to linger in your bloodstream from longer than intended.


If you’re a physically active person, your body is more likely to be in a state of constant detox. Using Flexeril will still get you the effects of the drug, but your body can get rid of the toxins much sooner. Since your body is already used to flushing out waste material, traces of cyclobenzaprine won’t linger for long.

Other factors like diet, the condition being treated, and age also play a small role in how long Flexeril lingers in your body. With this many factors, any test like a urinalysis has a good chance of catching traces of cyclobenzaprine in your body. 

The Dangers Of Cyclobenzaprine

The reason Flexeril can be so dangerous to so many people is that it affects the central nervous system. Cyclobenzaprine has a host of side effects like chest pain, dry mouth, and even skin rashes. People who overdose on the drug (a famous case being Whitney Houston) can end up suffering from a fatal heart attack.

People taking Flexeril should be careful to not mix it with other medications like antidepressants. A secondary effect of cyclobenzaprine is how similar it is to most tricyclic antidepressants, which can cause severe hormonal imbalances if taken improperly.

Cyclobenzaprine can also be extremely addictive if you aren’t careful. A report by the Substance Abuse and Mental Health Services Administration (SAMHSA) says that drug abuse with prescription drugs like Flexeril is getting higher every year. What complicates these statistics is that users don’t always abuse it willingly.

There are two ways that people can get hooked on cyclobenzaprine:

  • By deliberately overdosing on the drugs to get a temporary high
  • By becoming more tolerant of the drug over time, thereby needing a higher dose for the effects to work

The last part is why authorities classified cyclobenzaprine as a controlled substance in the United States. Depending on the state you’re in and the laws you fall under, possession of cyclobenzaprine without a current or valid prescription is illegal.

Why Would I Be Tested For Flexeril?

The potent effects of Flexeril (combined with the large percentage of people prone to the withdrawal syndrome) make most employers wary of people taking this medication.

If you’re applying for a job that involves delicate operations or working around hazardous materials, taking Flexeril might cost you that position. Some people that use it as a muscle relaxant report facing discrimination by potential employers because of the drug.

It’s easy to see why. Since most muscle relaxers like Flexeril can take a while to clear out of the system, employers are less likely to hire anyone reliant on the drug. Unexpected muscle spasms can be disastrous for employees operating heavy machinery, and any of the side effects of taking cyclobenzaprine can impact the quality of work.

While taking Flexeril isn’t illegal, some employers aren’t willing to take the risk of a present or potential employee misusing it. Flexeril can be addictive, and the withdrawal symptoms alone are enough reason for employers to look out for it. As a result, getting a positive result for it (even if you’re taking it with a prescription) can put your job at risk.

The hard fact is that employers are looking out for their bottom line regardless of the reasons you’re taking cyclobenzaprine. So if you’re taking Flexeril and need to hide it, what should you do?

Flexeril And Drug Tests

Luckily, most drug tests don’t look for cyclobenzaprine since it’s not classified as an illegal drug. And with the proper paperwork and a doctor’s note, you can reasonably explain away taking Flexeril for medication. But if that isn’t the case, then you have no choice but to prepare for the drug test the best way you can.

That’s why you need to find yourself products that stop cyclobenzaprine from showing up during testing. To do that, you need to be familiar with the ways you can get tested for the substance.

There are two ways Flexeril can pop up in drug tests:

  • Urine Test
  • Hair Follicle Test

Flexeril or cyclobenzaprine won’t show up in a standard drug testing kit, because it’s not like marijuana or cocaine which are explicitly illegal. Neither is it the top priority of most employers when they’re screening for drug use. But if you want to be sure that you’ll pass any drug test that you might face while taking it, then you need the right products to help you pass.

Each drug test works in different ways, so you need to find out in advance what the drug testing methods of your company look like. Once you do, here are the products that you should use to fool them.

The Urine Test

Your urine is a liquid record of everything you’ve ever put into your body, including drugs like Flexeril. Since cyclobenzaprine can stick around in your body for a long time, it’s possible to test positive for the drug even if it’s been a week and a half since your last dose.

Cyclobenzaprine also has a record of showing up on urine drug tests looking for tricyclic antidepressants, since its chemical composition is very similar to these drugs.

That’s why people will often fail a drug test if they’re taking Flexeril, even if they’re doing it legally. And while it’s possible to appeal the results of an initial drug test or provide documentation to show that you’re not doing anything illegal, it might be too late to matter to your employer.

How A Urine Test Works

Normal human pee is usually composed of:

  • Water
  • Assorted amino acids
  • Chemicals like urea, creatinine, and uric acid
  • Bacterial growth

Both laboratory-grade equipment and urine test kits will look for these compounds in your pee, and check them against the baseline of what normal, drug-free pee looks like. The problem arises when your pee has all these ingredients AND something else – in this case, traces of cyclobenzaprine.

Flexeril in particular has a long half-life: on average, it’ll stay in your body for about a week after your initial dose. That’s a lot of time for a urine test to catch traces of it in your body. Cyclobenzaprine can also stay for longer in your system depending on factors like body weight and dosage, which makes urinalysis an effective method of detecting these drugs.

The Product To Use: Fake Pee

However, you can fool urine drug testing by using a high-quality synthetic urine. Calibrated to resemble real urine that’s free of any drugs, it can help you pass your drug test with flying colors! One of the best urine products you can get right now is Clear Choice Sub Solution. Bring it on the day of the drug test, swap out your sample, and the lab technicians will be none the wiser.

If you want to know more about Clear Choice Sub Solution and how it works, read our review of the Best Synthetic Urine.

For The Hair Follicle Test

A hair follicle drug screen can be hard to fool since the toxins physically attach to your hair and you can’t scrub them off. Frequent hair washing won’t get rid of drugs like cyclobenzaprine, so you need something a little stronger than your supermarket shampoo and conditioner.

And since Flexeril and cyclobenzaprine stick around in your system, they’ll show up in your hair if there’s a lot of it. The detection time for these drugs in your hair is very long – up to two months on average. And with all the hair in our body, they can be difficult to hide.

How A Hair Follicle Test Works

A hair follicle test will take a sample of hair from your body (usually from your head) and scan it from the surface down to the core for traces of drugs. Since hair can be difficult to alter, the detection rate for drugs like cyclobenzaprine or Flexeril is around 95% percent, the same as most illegal substances.

Don’t think that you can just shave your hair and get away with it either: cyclobenzaprine and other drugs show up in ANY kind of hair that you have. So even if you take away the hair on your head, your pubic hair, leg hair, and eyebrow hair are all fair game for a hair follicle test.

Dyeing your hair doesn’t help either since most chemicals aren’t strong enough to penetrate the core of your hair strands. At best, you’ll just be called in for another round of testing once your hair grows back. The worst-case scenario is that you’ll be put under more scrutiny for doing something suspicious that close to testing day.

The Product To Use: Detox Shampoo

Old Style Aloe Toxin Rid Shampoo is designed to get the toxins and other traces of drugs out of your hair, it’s the most effective solution to bypass hair drug testing. Not only is it undetectable in a drug screen, but it can also help your hair withstand the cleansing process so you don’t arouse suspicion.

For a thorough review of Old Style Aloe Toxin Rid Shampoo, you can read our Best Hair Follicle Detox Shampoo guide.

Tips On Buying These Products

The best place to get these products would be online, since this isn’t the stuff that the authorities would like floating around on the pharmacy shelf. While that means that you can have an easier time getting your hands on these products, we have some disclaimers that you should keep in mind when buying:

Always make sure your source is legitimate. There are plenty of people out there who sell fake or substandard versions of these products, and that won’t fly with newer drug tests. Check whether your product is the latest version and whether the seller’s site is legit before cashing out.

Expect to spend. These products aren’t cheap once you factor in things like shipping and availability. But the cost for these products is a small price to pay to make sure that you keep your career intact. Thankfully, the sellers will often give some discount for repeat or bulk purchases.

Buy extras, just in case. Employers can administer urine or hair tests at any time. If your employer has an ironclad rule about not allowing drugs in the workplace, you might get caught unprepared if they ask you to go through surprise drug testing. Fortunately, the products we’ve recommended have a long shelf life and store well, so you can buy extras of them to prepare for this kind of situation.

Is Flexeril THAT Bad? Do I Really Need These Products?

Most field test kits and some laboratory exams don’t look for cyclobenzaprine specifically. Depending on the drug screen that you’re going through, you might be able to just keep taking this medication and not worry about the test.

It’s also possible that your workplace might be more permissive than other companies that they don’t mind you using stuff like Flexeril, especially if you have the right documentation. Even if you fail the test, showing the proper documents could be more than enough to get you out of trouble.

But those are BIG caveats and assumptions to make, and you won’t always have the luxury of knowing this stuff before the drug test. And because cyclobenzaprine is a regulated substance, it’s always better to just prepare for the worst.

Can I Naturally Detox From Flexeril?

Since your body can get rid of cyclobenzaprine in about eight to eleven days, you might think of just waiting out the detox period. That’s not a bad strategy if you have control over when they’ll test you.

But since the length of the detox can vary for everyone, it’s not worth it to take the risk to wait out the detoxing process before your urinalysis. Your employer can reschedule or move the date with no need to warn you, which can give you a bigger chance of getting caught for drug use.

And if you aren’t careful, the times that you need to take cyclobenzaprine can overlap with testing dates. For people taking Flexeril for maintenance medication, you may not have the luxury of waiting out your body’s detox process. In those cases, the only thing that you can do is to buy either synthetic urine or detox shampoo to guarantee yourself a passing result.

If you’re confident that you have the date of testing well in hand and you don’t take Flexeril that much or that often, you can wait for your body to get rid of all the traces. But if you want to be sure that you won’t trip during your laboratory exam, use one of the products we’ve recommended.


Flexeril and cyclobenzaprine won’t always show up on a drug test, but it’s best to be careful about the possibility that they will. Even if you’re taking these drugs legally, you should always keep in mind that employers can and will take that into account when it comes to your career. If you aren’t careful, you can lose your job.