The human body metabolizes drugs differently depending on the type of drug. Some drugs are metabolized rather quickly (e.g., drugs that are water-soluble), and other drugs are metabolized rather slowly (e.g., fat soluble). In addition, the maximum length of time that drugs can be detected in a person’s body depends on the method of detection. Most sources use urinalysis as the means of detecting drugs; however, drugs can be detected in someone’s hair for significantly longer periods of time than via urinalysis.

The metabolism of drugs is largely undertaken by the liver, but very small amounts are metabolized through the skin and lungs. A good number of estimates regarding the length of drug detection are based on the half-life of the drug, which refers to the amount of time it takes the body to metabolize a specific concentration of the drug by half. The figures that are generally quoted are standard figures but will vary in specific cases based on individual differences in metabolism, weight, gender, and other factors.

How long do drugs stay in your system?


The two most commonly abused drugs in the United States are tobacco and alcohol. Individuals who chronically use alcohol can develop serious issues with alcohol use disorders, physical dependence, and a number of potential serious health hazards that can include cardiovascular issues, cirrhosis of the liver, and dementia. Alcohol is one of the drugs that has no stated half-life; instead, the concentration of alcohol in the bloodstream is used as a measure of its presence, and there is a steady rate of decline in the concentration of alcohol in the blood. A number of factors can affect this rate of decline, including those mentioned above and other factors, such as if an individual has eaten, if an individual takes alcohol with other drugs, etc.

How long does alcohol stay in your system?

Of course, different forms of alcoholic beverages have different concentrations of alcohol. The standard used by most sources is to compare 12 ounces of normal beer (at about 5 percent alcohol), 5 ounces of table wine (at about 12 percent alcohol), and 1.5 ounces of 80 proof liquor as all having the same amount of pure alcohol in them (about 0.6 ounces of pure alcohol).

Sources vary on the rate of metabolism for alcohol but it is generally quoted that around 0.5 ounces of pure alcohol per hour are eliminated from the body under normal circumstances. This means that your body would totally metabolize the alcohol in one of the above drinks within a little over one hour if you did not ingest any more alcohol. The situation is complicated though because the liver begins metabolizing alcohol even when people are still drinking. It becomes difficult to come up with a standard figure regarding how long alcohol is detectable through urinalysis. The general figure, in most cases, is that alcohol is undetectable 18-24 hours after an individual stopped drinking; however, there are certain metabolites of alcohol that may be detected for lengthier periods of time.

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Barbiturates are drugs that were developed to treat issues with anxiety, seizures, as aides for sleep, and as mild tranquilizers. These drugs are no longer prescribed as frequently as they once were due to their high potential for the development of physical dependence and abuse. Instead, the benzodiazepines have largely replaced use of barbiturates in the United States. Nonetheless, barbiturates are still prescribed for certain types of disorders (e.g., seizure disorders) and for certain groups of individuals (e.g., in some cases, for elderly individuals).

The half-life of barbiturates depends on whether or not the drug is short-acting, intermediate-acting, or long-acting. A few general examples follow:

How long do Barbiturates stay in your system?
  • Seconal (secobarital) is a short-acting barbiturate with a half-life of approximately 20 hours (reported to range anywhere from 15 to 40 hours). It can be detected for up to 72 hours in urine in most cases.
  • Fioricet (butalbital) is an intermediate-acting barbiturate that has a half-life of approximately 35 hours. In most cases, it can be detected by urinalysis for up to seven days.
  • Phenobarbital is a long-acting barbiturate with a half-life of approximately 79 hours (reported to range from 53 to 118 hours). In most cases, it can be detected in the urine for up to 15 days.

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As mentioned above, benzodiazepines are drugs that basically replaced barbiturates. They generally have the same mechanism of action (as central nervous system depressant drugs that work on the neurotransmitter GABA) and the same medicinal uses as barbiturates. Benzodiazepines are popular drugs of abuse; however, they are commonly abused in combination with other drugs and not commonly the primary drug of abuse. For this reason, their detection can be rather complicated.

Benzodiazepines are also divided into short-acting, intermediate-acting, and long-acting classes. Descriptions of several of the common benzodiazepines from each class follow.

How long are Benzodiazepines in my system?
  • Halcion (triazolam) is probably the most familiar short-acting benzodiazepine. The half-life of Halcion is rather short at 1-6 hours. It is typically detectable in urine analysis for up to 48 hours.
  • Ativan (lorazepam) is an intermediate-acting benzodiazepine. Its half-life is reported to be 12-18 hours, and it can be detected in urinalysis for about five days after last use.
  • Klonopin (clonazepam) is another familiar intermediate-acting benzodiazepine. Its half-life is 30-40 hours, and it can also be detected in the urine for up to five days.
  • Xanax (alprazolam) is probably the most recognized intermediate-acting benzodiazepine. Its half-life is 6.5-27 hours, and it is detectable in urine for about five days after last use.
  • Valium (diazepam) is probably the most recognized long-acting benzodiazepine. The half-life of Valium is 30-56 hours. Urinalysis can detect the presence of Valium for between 10 days to two weeks after last use.

Individuals who chronically abuse long-acting benzodiazepines may have windows of detection via urinalysis for up to 30 days because these drugs are lipophilic (fat-soluble), and those who take large amounts of these drugs will develop significant tolerance to them. This means that individuals can take extremely high doses of this drug and continue to take high amounts of the drug that would be potentially dangerous to take by those without such tolerance. This can result in very high amounts of the drug in the system that need to be eliminated. The drug is eliminated based on its half-life, and the total time to eliminate the drug is based on the original concentration of the drug in the system.

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Cannabis products are legal in certain states. Some states have legalized the use of cannabis products for medicinal purposes only, whereas others have legalized it for recreational use as well as for medicinal purposes.

The major psychoactive substance in cannabis is THC (delta 9-tetrahydrocannabinol); however, there are a number of other psychoactive substances in the drug as well. For purposes of this article, the detection of THC will be used to represent the detection of different cannabis products in one’s system.

THC is fat-soluble and eliminated relatively slowly from the body. It appears that the half-life of THC is about 30 hours; however, detection of THC in one’s urine depends on how much cannabis one had used and how often they use it. A few examples follow.

how long does marijuana stay in your system

  • A person with no previous use of cannabis or who has not used cannabis for quite some time will most likely not have detectable urine samples about 72 hours after use.
  • People who use cannabis products on a moderate level (clinically defined as four times per week) will have detectable amounts of THC in their urine for up to five days.
  • Daily users of cannabis products will have detectable traces of THC in their urine for up to 10 days.
  • Chronic long-term users of marijuana may have detectable traces of THC in their urine for up to 30 days or even longer.

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Ketamine is classified as a dissociative hallucinogenic and was once very popular as a club or rave drug. While it was developed as an anesthetic drug for humans, it is now typically used primarily as an anesthetic by veterinarians, although it still has some limited use in humans. The half-life of ketamine is reported to be 2-5 hours, and it can be detected in urine for up to 48 hours after discontinuation.

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LSD (Lysergic Acid Diethylamide)

LSD is a hallucinogenic drug that produces alterations in perceptual experiences, hallucinations, and even dissociative experiences. LSD is water-soluble and has an extremely short half-life of 3-6 hours. It is most likely excreted very quickly in individuals. Since it is taken in very small doses in most cases, it is only detectable for one or two days; in many cases, it may even be detectable for significantly shorter periods of time.

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Narcotic Drugs

Opiate drugs are prescription drugs that are typically prescribed for the control of pain. All of these drugs are potentially quite addictive, and abuse of prescription narcotic drugs is a major issue in the United States. Because tolerance develops rapidly to these drugs, many individuals who abuse them often take extremely high doses, and detection of the drug in the system of chronic abusers can be quite variable.

  • Heroin is a drug that has no stated medicinal uses although it was developed as an alternative to morphine for pain control. The half-life of heroin is approximately six hours, and it is detectable via urinalysis for an average of about three days. Most sources report a range of 2-4 days.
  • Morphine is a drug that is commonly used in the medical profession for the control of pain, and it has a half-life of 1.5-7 hours. It can also be detected in urine for about 2-4 days.
  • Hydrocodone is the narcotic ingredient that is found in a number of different prescription medications such as Vicodin. It has a half-life of about four hours, and it can be detected in urine for about three days after use.
  • Oxycodone is the active ingredient in OxyContin, and it is detectable 2-4 days after use via urine analysis. It has a half-life of about 4-5 hours.

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Stimulant drugs compromise a number of different types of drugs, both illicit and drugs with medicinal uses. Stimulants were designed for a number of medical reasons, and they are used today to stimulate people who have particular types of illnesses that make them sluggish and lethargic (e.g., HIV, certain types of delirium, depression, sleep disorders, etc.), to improve focus, to lose weight, and to stay awake. Several stimulant drugs of note are outlined below.

  • Amphetamines are the stimulants that are used in medicinal drugs, such as Ritalin and Adderall, and in a number of other substances, including diet aids. The average half-life of amphetamines is 8-11 hours. Amphetamines typically have a detectable window via urinalysis for about three days.
  • Cocaine has an extremely short half-life that may be less than an hour and for most individuals is probably not more than an hour. It is eliminated from the system very rapidly and is generally detectable via urinalysis for 24-48 hours; however, a number of metabolites for cocaine are detectable for significantly longer periods of time after discontinuation.
  • Methylenedioxymethamphetamine (MDMA) is the active ingredient in the drug ecstasy. It is detectable in urine for periods of around 48 hours due to its relatively short half-life of about 6-8 hours.

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The detectable periods for drugs in the system represent the best clinical methods of detecting the presence of drugs in a person’s body. However, certain minute quantities of drugs that are undetectable by urinalysis and even by other methods most likely remain in the person system for lengthier periods of time. While most clinical sources typically use the clinical methods of detection to measure the length of time that certain drugs remain in a person’s system, many sources suggest that the effects of chronic drug use are not negated until one is abstinent for several years following their use. For certain types of drugs, the physical changes that are associated with chronic use and abuse may remain indefinitely.

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