What’s the Difference Between Urine, Saliva, Hair Follicle, and Blood Drug Tests?

There are a number of drug testing options: urine tests, saliva tests, hair follicle tests, and blood tests. Here’s what you need to know about each type.

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What’s the Difference Between Urine, Saliva, Hair Follicle, and Blood Drug Tests?

There are a number of drug testing options: urine tests, saliva tests, hair follicle tests, and blood tests. Here’s what you need to know about each type.

Your job is going to give you a drug test soon. Should you be worried? Can you pass it? Well, there are a number of factors in play, most notably, what kind of test they’ll be giving. There are a number of options: most notably urine tests, saliva tests, hair follicle tests, and blood tests. What’s the difference between them? Which one is most accurate? Here’s what you need to know.

Urine Tests

This is the most common type of drug test, used by about 95% of employers. The subject pees into a cup, and the cup is tested for illicit substances. This can either be a basic test, performed on site, or a more comprehensive one, wherein the urine is sent to a lab for thorough analysis.

On the one hand, there are a number of ways to pass a urine test and get a negative reading, even with drugs in your system. On the other hand, since it’s the most common type of test, over the years, the tests have evolved and grown more sophisticated. Many of the most common methods of gaming the system, such as drinking a lot of water or substituting synthetic urine, will set off red flags on many of today’s tests. In response, employers will call for a retest, with the sample sent to the lab, where it becomes much more difficult to mask the presence of drugs.

Saliva Tests

This method is popular with some employers because it’s easy and inexpensive. The test can be performed by the employer on site, with a simple swab of the inside of the subject’s mouth. The sample is then sent to a lab, where it’s analyzed for the presence of a variety of drugs and substances.

Saliva tests are very accurate, but they have only a very short window. Marijuana, for instance, which famously remains in your blood and urine for up to four weeks, can disappear from your saliva in as little as 10 hours. The window for other substances can be anywhere from a couple of days to a couple of hours.

Some employers like this aspect of the test, as it makes it easier to uncover habitual drug users, as opposed to someone who just smoked weed once at a party a couple of weeks ago. However, this small window also makes the test easy to pass, with only a couple of days’ notice.

Hair Follicle Tests

Many of these tests can be conducted by your employer. For hair follicle drug tests, however, a trained professional must be the one to collect the sample. That sample is then sealed and sent to a lab for analysis.

Hair tests are popular among employers because of their reputation. They’re virtually impossible to scam. They also tend to have a much larger window wherein a person can test positive. Substances like cocaine and methamphetamines, which are undetectable in urine tests after only a few days, can remain in your hair follicles for months. It can also be used to test for opioids, steroids, and even alcohol.

There are also drawbacks, however, First, once collected, it’s very easy for the sample to become contaminated. This is why it must be collected by a trained professional: to avoid anything else coming into contact with the sample which could alter the results of the test.

Furthermore, while the test is great for detecting long term drug use, it’s less effective at detecting recent drug use. This is because hair grows slowly. Once a substance is ingested, it can take a few days for it to end up in your hair.

Blood Tests

These are the most accurate drug tests. They’re virtually impossible to cheat. Like with hair tests, a trained professional must collect the sample, which makes substitution impossible. There’s also very little you can do to alter the chemical composition of the blood in your body so that a particular substance isn’t detectable.

Blood testing is also expensive. Unlike many other tests, it can’t be done on site. Subjects instead need to be sent to the lab to have their blood taken. And the window wherein certain drugs are detectable in your bloodstream is very small. Going to all that hassle and expense to measure drug use for only the last few days makes this method of testing less appealing for many employers.

There are other methods of drug testing as well. Sweat tests, for instance, are common for subjects on probation or parole. A patch is left on the skin for two full weeks, collecting sweat that can then be analyzed for a variety of substances. Some breathalyzer tests have also been designed to detect marijuana and other drugs, in addition to alcohol.

All of these tests have their strengths and weaknesses. How you should proceed when they’re given to you depends on which test you take, how long it’s been since your last drug use, and a variety of other factors. However, if you know in advance what the test will be, it’s easier to make preparations that make passing more likely. It’s also important to know your rights. Which tests are allowed in your area, and are there any specific laws or guidelines governing how and when they can be administered? Knowledge is power, and understanding these drug tests and how they work will make it easier for you when you take them, and help you to pass.


Founded in 1999, UrineTheClear® continues to be at the forefront of the drug-testing solutions industry with innovative products and procedures. We were the first on the market to dehydrate human urine, the first company to offer a 300% guarantee and continue to be the only company that utilizes GC/MS (gas chromatography/mass spectrometry) when testing our urine.