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How Long Do Benzodiazepines Stay in Your System?

A drug test can detect benzodiazepines in the urine within two to seven hours of last use. Long-acting benzos, such as Valium, may remain detectable for up to 10 days after consumption. Metabolites of benzodiazepine can remain detectable in the hair for up to one month.

Benzodiazepines can remain in a person’s system for up to a month after use. Typically used to quell anxiety and tension, the depressant drug has a high potential for abuse. Physicians can detect benzodiazepines in a person’s system by performing tests on a sample of their hair, saliva, urine or blood.

Benzodiazepines, such as Xanax and Valium, are central nervous system depressants used to treat anxiety, acute stress reactions and panic attacks. Doctors typically prescribe benzos as a short-term therapy because of the addictive properties of the drug. Physicians can determine if benzodiazepines are present in an individual’s system by performing blood tests, urine tests, hair tests and saliva tests.

Currently one of the most prescribed depressant medications, benzodiazepines are classified as Schedule IV drugs under the Controlled Substances Act. When mixed with other depressants such as prescription opioids and alcohol, benzodiazepines become more potent, increasing the risk for serious or life-threatening complications. Benzodiazepines such as Rohypnol are popular for facilitating sexual assaults.

Testing for Benzodiazepines

Benzodiazepines will produce a positive urine test result as early as two to seven hours after an individual takes the drug. The drug clearance rate is the length of time a benzodiazepine will remain detectable in the body, and it varies from drug to drug.

Long-acting benzos, such as Valium, can be detected in the urine for up to 10 days. Halcion and other short-acting benzodiazepines can be detected for up to two days.

Approximate Detection Time for Benzodiazepines in Urine

TYPE OF BENZODIAZEPINE DETECTION TIME
Long Acting Valium (diazepam) Up to 10 days
Nordiazepam
Intermediate Acting Xanax (alprazolam) Up to five days
Ativan (lorazepam)
Serax (Oxazepam)
Restoril (temazepam)
Librium (chlordiazepoxide)
Klonopin (clonazepam)
Rohypnol (flunitrazepam)
Short Acting Halcion (triazolam) Up to two days
Dalmane (flurazepam)

Source: Mayo Medical Laboratories

People tested for benzodiazepines include athletes, drug rehab clients, employees, hospital patients and military personnel.

Urine Tests

A urine test followed by a urinalysis is a common way to determine whether the intermediate-acting benzo Xanax is present in an individual’s system. After the body metabolizes the drug, about one-fifth of the oral dose remains in the urine. Low-dose Xanax users may test positive for the drug for up to four days after ingestion, and heavy users may produce a positive result for up to a week after ingestion.

Hydration affects urine drug tests because high fluid intake dilute the drug and produce a false negative result.

Low doses of benzodiazepines or long intervals between use may produce a negative result if levels of the drug in urine fall below the detection cutoff. In addition, the interval of time between using the drug and taking a urine test may affect whether levels of the drug in the body are high enough to trigger a positive test result.

Metabolism also affects the outcome of urine tests. Each person’s metabolism rate is unique and varies depending on age, gender, ethnicity and the presence of liver or kidney impairment. Slow metabolism rates can mean the drug will be present in the urine for a longer time. People with fast metabolism rates will break down the drug quickly, reducing the detection window.

Several other factors influence how long a drug stays in a person’s urine, including:

These factors may result in false positives. In the event of a positive test result, physicians should determine if the patient was prescribed a benzodiazepine and followed instructions for use.

Blood Tests

Blood tests to determine the presence of benzodiazepines in the body are more invasive than urine tests but are sometimes necessary. If a patient is hospitalized, doctors may need to give a blood test to know whether the person is intoxicated with alprazolam.

Blood tests can detect the presence of alprazolam within hours of intake, and the blood sample may test positive for up to a day after intake. However, blood tests have shorter detection windows than urine tests.

Hair Tests

Detecting benzodiazepines with a hair sample is possible. When a person ingests alprazolam, the drug accumulates in outgrowths of hair follicles throughout the body and head. Hair testing requires a hair sample of 20 to 50 strands for laboratory analysis. Through a test called a benzodiazepine radioimmunoassay, experts will be able to determine the presence of alprazolam for up to four weeks after intake.

Because it takes roughly one month for one centimeter of hair to grow, hair tests performed within a few days of ingestion may produce inaccurate results. It is more difficult to detect alprazolam with hair tests than to detect long-acting benzodiazepines such as diazepam.

Saliva Tests

A saliva test can detect alprazolam for up to 2.5 days after ingestion. Saliva tests have a longer detection window than blood tests but a shorter window than urine tests. An adequate amount of oral fluid is required for saliva tests. They tend to be more costly than urine tests, so they are not as common.

Types of Benzodiazepines

Benzodiazepines can be short-, intermediate- or long-acting. The classification depends on the drug’s elimination half-life, which describes the length of time until the concentration of the drug in the body is reduced by one-half.

Short-acting benzos typically leave the body faster than long-acting ones; they have an elimination half-life of one to 12 hours. Intermediate-acting benzos have an average elimination half-life of 12 to 40 hours. Long-acting benzos have an elimination half-life of 40 to 250 hours.

Benzodiazepine Half-Lives and Time to Peak Level in Blood

NAME OF BENZODIAZEPINE TIME TO PEAK LEVEL HALF-LIFE
Xanax (alprazolam) One to two hours 12 hours
Lexotan (bromazepam) One to four hours 20 hours
Librium (chlordiazepoxide) One to four hours 100 hours
Klonopin (clonazepam) One to four hours 34 hours
Tranxene (clorazepate) 0.5 to two hours 100 hours
Valium (diazepam) One to two hours 100 hours
Dalmane (flurazepam) 0.5 to one hour 100 hours
Ativan (lorazepam) One to four hours 15 hours
Mogadon (nitrazepam) 0.5 to two hours 30 hours
Serax (oxazepam) One to four hours 8 hours
Doral (quazepam) 1.5 hours 25 to 41 hours
Restoril (temazepam) Two to three hours 11 hours
Halcion (triazolam) One to two hours 2 hours

Source: Medscape

Drugs with longer elimination half-lives will remain in the system longer. The rate at which benzodiazepines take effect depends on the drug’s ability to cross the blood-brain barrier. Benzos, such as diazepam, that dissolve in fat act faster than water-soluble benzos, such as lorazepam. The peak blood concentrations of benzos typically occur within the first three hours of intake.

One dose of a fat-soluble benzo will have a shorter duration of action than a similar dose of a water-soluble benzo. This is mainly because of the rapid redistribution from the central nervous system to peripheral sites. While intermediate-acting lorazepam affects the central nervous system longer than long-acting diazepam does, the latter metabolizes into active intermediates with longer half-lives, which extends its effects. Hence, diazepam stays in the body longer than lorazepam.

Factors Influencing How Long Alprazolam Stays in the Body

Several factors influence how long intermediate-acting alprazolam stays in an individual’s body. While one person may process the drug in three days, a different person may take longer. The clearance rate of a drug depends on individual factors, drug dosage, frequency of use and other drugs used.

Individual Factors

Factors such as age, physique, genetics, liver and kidney function, metabolic rate and urinary pH affect how long alprazolam stays in the system.

Elderly people take longer than young people to process alprazolam from their system, which may be because of a change in metabolic rates, altered blood flow to the liver or deterioration in internal functions.

An individual’s height, weight and body fat percentage may influence the clearance rate of alprazolam. A short, lightweight person will take longer to clear the drug than a tall, heavyweight person. Compared with the smaller person, the larger person is ingesting a smaller amount in proportion to their body size.

Individuals with impaired liver function tend to process alprazolam more slowly than those with normal liver function. Liver disease and cirrhosis extend alprazolam clearance times.

Drug Dosage

People who take higher doses of alprazolam will take longer than those who take lower doses to excrete the drug from their system. A normal alprazolam dose ranges from 0.25 mg to 4 mg, but sometimes people have to exceed the 4 mg dosage because of tolerance, a substance use disorder or dependence.

Frequency of Use

The frequency of use of alprazolam determines how fast the body purges the drug. Long-term users will take longer than those who have used the drug over a short period to clear the drug. Developing a tolerance often causes people to increase their dosage, which extends the detection window and causes the drug to accumulate in a person’s system.

Use of Other Drugs

Ingesting other drugs at the same time as alprazolam may change the body’s ability to process and excrete the drug. Taking medications such as cimetidine, erythromycin, itraconazole, ketoconazole and ritonavir may result in delayed liver clearance. Oral contraceptives and SSRIs such as Prozac also delay the metabolism and expulsion of alprazolam from the system.

Similarly, people may take drugs to accelerate the metabolism of alprazolam. Such drugs include carbamezepine, glucocorticoids, phenytoin, progesterone, nafcillin, phenobarbital and St. John’s wort. Studies also revealed that smokers may have a slightly higher clearance rate than nonsmokers.

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