5 Factors That Determine Amphetamine Half Life


If you’ve taken an amphetamine recently—whether illegally or by prescription—you might be wondering, “How long do amphetamines stay in your system?” The answer to this question will be especially important to know if you need to take (and pass) a drug test soon.

In this article, we explain how long amphetamines stay in your system, the key factors that affect how long they stay in you, and how to get them out of your system more quickly.

Feature image: Alex Dodd/Flickr


How Long Do Amphetamines Stay in Your System?

Let’s get right down to it: how long do amphetamines stay in your system? We’ll start by looking at two basic elements:

  • The type of drug test you take
  • The type of amphetamine you use

There are many kinds of amphetamines, or stimulants. Some are illegal, such as meth, whereas others are legal and available by prescription, such as Adderall and Ritalin (which are often used to treat ADHD).

Unlike cocaine, the effects of amphetamines can last for hours. Depending on the amphetamine, effects can start to show immediately (if injected) or take anywhere from three to 20 minutes (if snorted or ingested).

But amphetamines can be detected in you long after the effects wear off. The following chart shows approximately how long you’ll need to wait until you can pass different drug tests:

Drug Test How Long Detectable Levels Remain
Urine 2-4 days
Saliva Up to 3 days
Hair Up to 90 days

Source: Amphetamines.com

Another factor that determines whether amphetamines will be detectable in your system is the type of amphetamine you take. The urine test is the most common test used to detect amphetamines, so we’ve listed

Type of Amphetamine How Long Detectable Levels Remain in Urine
Amphetamine Up to 3 days
Methamphetamine Up to 3 days
3,4-Methylenedioxyamphetamine (MDA) Up to 2 days
3,4-Methylenedioxymethamphetamine (MDMA) Up to 2 days
Ephedrine/pseudoephedrine Up to 5 days

Source: DrugRehab.com


What Affects How Long Amphetamines Stay in Your System?

According to the American College of Neuropsychopharmacology, the average amphetamine half life is 12-14 hours.

But the exact amphetamine half life can vary depending on five major factors:

  • How many amphetamines or how high of a dose you take: A higher concentration of amphetamines in your system forces your body to process more of the drug at once, making it take longer to flush out.
  • If you’ve taken amphetamines before or are a regular user: If taking amphetamines is routine for you, your body will take longer to get rid of it each time you take it.
  • Your metabolism: Those with faster metabolisms will eliminate amphetamines from their bodies faster than those with slower metabolisms.
  • Your age and weight: The older and more overweight you are, the longer it’ll take for your body to flush out the amphetamines. By contrast, the younger and leaner you are, the less time your body will need to get rid of the drug.
  • How you ingest the amphetamine: Pills generally take the longest to get out of your system (and are the slowest to show effects), whereas smoking, injecting, or snorting will expel the drug faster.


How Can You Get Amphetamines Out of Your System Faster?

There are a couple of ways you can get amphetamines to leave your system faster.

One is to stay hydrated. The more dehydrated you are, the longer it’ll take for your body to get rid of the amphetamine. Thus, drinking a lot of water can help your body eliminate the drug faster (or, at the very least, keep it from staying in you longer than an average length of time—see the charts above).

The other trick is to exercise. Getting your body moving can help you flush out water and other toxins more quickly.

That said, don’t drink way too much water or exercise until you feel as if you’re going to pass out. Be kind to your body!

Hopefully, after reading this article, you now have a clearer idea as to how amphetamines and drug tests work, and what you can do to get your body to process the drug safely and fast.