How Long Do Drugs Stay in Your System (Drug Half Lives Explained)

If you are wondering “how long do drugs stay in your system” the answer will vary widely depending on: the type of drug, drug dosage, how often the drug is used, what type of test is being run and many other personal factors.

For example, a urine drug test, drugs can last in your system for up to 30 days for marijuana, but only up to 3 or 4 days for other substances like opiates or benzos. Meanwhile, if you are taking a hair drug test, all substances generally last up to 90 days.

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The factors that determine if and when a drug will show up in a test varies widely. The most common factor impacting detection is the type of test being administered. You will also have a higher concentration of the substance in your system if you use it frequently.

How long will drugs show in a urine test?

  • Alcohol: 10-12 hours
  • Methamphetamine: 2 to 5 days
  • Benzodiazepines: Up to 7 days
  • Cannabis (Marijuana): 1-30 days
  • Cocaine: 1 to 8 days
  • Opioids: 2-5 days
  • Heroin: 2 to 3 days
  • PCP (Phencyclidine): 5 to 6 days

LSD, Mushrooms, Synthetic Cannabinoids, Ecstasy (MDMA) will not be detected by typical drug testing.

How long do drugs stay in your blood?

A blood drug test is one of the least common ways of detecting a substance as it is invasive, expensive, and typically only detects a substance for a short period (about 2-12 hours after last use). For this reason it’s often only used in an emergency situation.

How far back does a hair follicle test detect drugs?

Nearly every substance tested remained detectable in a hair follicle test for up to 90 days. This included hair drug tests for prescription and illicit drugs as well as alcohol.

How long do drugs stay in your saliva?

  • Alcohol: Up to 24 hours
  • Methamphetamine: 1-48 hours
  • Cannabis (Marijuana): Up to 24 hours
  • Cocaine: 1-36 hours
  • Opioids: 1-36 hours
  • Heroin (Opiate): 1-36 hours

LSD, Mushrooms, Synthetic Cannabinoids, Ecstasy (MDMA) will not be detected by typical drug testing.

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Individual Factors Leading to Drug Detection

Higher doses of drugs can take longer to metabolize and eliminate from the body because the body can only process a certain amount of the drug at a time. At higher doses, these substances can take longer to break down and eliminate from the body.

Regular use of drugs and substance abuse can result in the drug building up in the body, which can increase the amount of time it takes to eliminate the drug. This is seen most commonly with marijuana drug screens, as it can be detected in urine samples for a longer period — up to 30 days for frequent users.

Factors such as body weight, height, and body fat percentage can influence how long drugs stay in the body. Drugs tend to accumulate in fat cells, so people with higher body fat percentages may eliminate drugs more slowly than people with lower body fat percentages. Along with these factors, things like ethnicity can even play a role due to genetic differences between individuals.

As we age, our bodies become less and less effective at metabolizing and eliminating drugs and foreign substances. This means that older adults may have drugs last longer in their system than younger adults.

The liver and kidneys are responsible for metabolizing and eliminating drugs from the body. If these organs are not functioning properly, drugs may take longer to be eliminated. Again, age is a factor in the functions of these organs.

How a drug is taken (such as smoking, snorting, or injecting) can affect how long the drug stays in the body.

Along with these factors, the most important thing that will impact how long a drug will stay in your system is the type of drug and the half-life of the drug.

What does the half life of a drug mean?

The Importance of Drug Half-Lives

Drug half-lives are a good measure for anyone trying to determine the period of time and how long a drug will be present in their body. That said, some drug tests, especially hair tests, can still pick up traces of the drug long after 4 to 5 half-lives have passed. That said, learning some of the most common half-lives will be a good indicator for determining intoxication and some forms of detection.

The half-lives of drugs are all different and while you may not feel the effects of these substances any longer, they are still able to be detected through a drug test.

To get a better idea of how long drugs will stay in your system and show up in certain types of drug tests, take a look at the chart below:

bottle and glass depict addiction


Urine Test: Up to 72 hours
Saliva Test: Up to 24 hours
Hair Test: Up to 90 days


Urine Test: 2-3 days
Saliva: N/A
Hair Test: Up to 90 days

pill pack to depict addiction


Urine Test: 2-3 Days
Saliva Test: N/A
Hair Test: Up to 90 days

bag with granular substance to depict addiction


Urine Test: 2-3 days
Saliva Test: 1-36 hours
Hair Test: Up to 90 days


Urine Test: Up to 30 days
Saliva Test: Up to 24 hours
Hair Test: Up to 90 days

icon of a syringe and injectable opioid thats addictive


Urine Test: 1-3 days
Saliva Test: 1-48 hours
Hair Test: Up to 90 days

While the drug chart above may help you determine how long certain illicit drugs stay in your system, you may be wondering about the half-lives or detection duration of certain prescription drugs:

Fentanyl will be detectable in urine for 2 to 3 days after use.

Vyvanse is the brand name for lisdexamfetamine dimesylate. It is an amphetamine with a high potential for abuse. It has a half-life of less than one hour. As an amphetamine, it is detectable in a urine test for 2 to 3 days.

Xanax is the brand name for alprazolam, used for anxiety and panic disorders, and has an average half-life of 11.2 hours. Xanax can be detected in a urine drug test for 36 hours for a single dose but can stay in the system longer, up to 5 days for short-acting benzos or as long as 30 days for long-acting benzos, for people who use the drug regularly.

Valium is also a benzodiazepine but is a branded form of diazepam. It has a half-life of 1 to 3 hours.

How to pass a drug test?

The only sure way to pass a drug test is to abstain from drugs. Companies may accept various doctors notes or medical prescriptions to explain the detection of various substances, but this will not prevent them from showing up.

The best way to get drugs out of your system, in a safe manner, is to go through a medically supervised detox due to the dangers and life-threatening complications that can arise from drug and alcohol withdrawal when trying to quit cold turkey.

If you are worried about your situation, meet with a doctor or addiction professional to get the best advice on what to do. During a medical detox, clients will be medically monitored as they go through the early stages of sobriety and the symptoms of withdrawal.

Drug withdrawal occurs when an individual has developed a physical and/or psychological dependence on their substance of choice, leading to uncomfortable and dangerous withdrawal symptoms when those substances are absent. The problem can become especially dangerous and life-threatening when dealing with alcohol, benzo, and opioid withdrawal. Withdrawal from these drugs can lead to:

  • Seizure
  • Hallucinations
  • Delirium Tremens
  • Respiratory Depression
  • Coma
  • Death

Drug addiction is not something to take lightly. If you think that you or a loved one has an addiction problem and are worried you may experience withdrawal when trying to quit, it is vital to reach out to addiction professionals.

Our team at The Hope House has dedicated case managers, experienced clinicians, and addiction experts ready to help provide around-the-clock care during your time in our detox and inpatient rehab programs.

Call our team and get the process started.

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