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How Long Does Serax (Oxazepam) Stay In Your System

Isaac Alexis, M.D., AAMA, AMP-BC

Medically reviewed by

Isaac Alexis, M.D., AAMA, AMP-BC

May 13, 2019

Serax (oxazepam) is a benzodiazepine that is often prescribed to treat anxiety, insomnia, and alcohol withdrawal symptoms. This sedative drug can stay in a person’s system up to 30 hours after last use.

Serax stays in a person’s system for about 30 hours. The half-life of Serax can range anywhere from five to 15 hours. This means that after 15 hours, about half the dose will remain in a person’s system.

The exact amount of time that Serax will stay in your system depends on several factors, including your overall health. If a person suffers from renal (kidney) or liver problems, it could take additional time for Serax to be cleared from their body.

Serax is a benzodiazepine and a central nervous system sedative. This class of drugs works by slowing down the systems of the body.

How Long Does Serax (Oxazepam) Take To Work?

Serax is different from other benzodiazepines, as it can take longer for a person to feel the drug’s sedative effects. Serax reaches its peak concentration levels within one to four hours after last use. During that time, most people experience the sedative effects of the drug, including drowsiness or feeling dizzy.

Serax and other benzodiazepines are metabolized by the liver. When a person takes Serax, their liver begins to break down the drug into agents called metabolites. Some people may experience the effects of Serax faster than others, depending on their metabolism and liver function.

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Serax comes in an oral capsule, and doses may be prescribed up to four times per day. Once a dose has been taken, the drug will stay in a person’s system for at least one day.

Serax (Oxazepam) Detection Time

Serax can be detected in a person’s system anywhere from two to 30 hours after last use. People who take Serax will likely experience the effects of the drug within several hours. These time estimates can change based on a person’s age, body mass index, and metabolism.

There are several reasons why a person may wonder how long Serax stays in your system. The most common reason is for drug screenings, as many people take required drug tests for employment or medical purposes.

Others may be curious about Serax detection time because they want to know how long the drug will be active in their body. They may be concerned about Serax interacting with another medication.

It can be extremely dangerous to take other drugs while on Serax (especially opioids). Mixing opioids with benzodiazepines can lead to overdose or even death.

Serax may cause side effects like drowsiness, dry mouth, and frequent urination. As peak levels of Serax decrease in the body, these effects should decrease or stop altogether.

People who take Serax for a long period of time may also develop a tolerance to the drug. This means that the body requires a higher dose of Serax in order to get the same effects.

Having a tolerance can lead people to take higher doses than directed. Serax can be habit-forming, so it’s important to take this drug exactly as prescribed.

Drug Test Types That Detect Serax (Oxazepam)

Central nervous system depressants (including benzodiazepines) are some of the most commonly abused drugs. Benzodiazepines can lead to tolerance, dependence, and addiction. Because of this, schools, doctors, and employers may require routine drug screenings.

Several types of tests can detect a benzodiazepine like Serax in a person’s system, including:

  • Urine Screening: This is the most commonly used drug screening, and usually shows results from the past one to three days
  • Blood Test: Benzodiazepines like Serax can be detected in plasma (the colorless fluid part of blood) for several hours after last use
  • Saliva Swab: Oral swab tests can detect benzodiazepines for up to 24-36 hours after last use
  • Hair Test: While it’s uncommon to use a hair test for Serax, hair follicle screenings can often detect substances up to 90 days after use

If you have a prescription for Serax (oxazepam) and are worried about passing a drug test, simply alert the person administering the drug screening. You will likely be asked to provide proof of your prescription.

Factors That Influence How Long Serax (Oxazepam) Is In Your System

The amount of time Serax can stay in your system will differ, based on a number of personal factors. Genetics, overall health status, and size can all play a part in determining how long Serax will remain in your body.

Serax (oxazepam) detection time can be altered by additional factors, including:


People of an advanced age may have longer detection windows for benzodiazepines like Serax.
As people age, their metabolism slows down. This can affect how long it takes for a person’s liver to fully metabolize the drug and clear Serax from the body.

Amount Taken

When a person takes Serax over a long period of time, it may take longer for the drug to leave their system. Serax is usually prescribed short-term, but taking the drug every day for the length of the prescription could result in larger amounts of Serax that remain traceable in the body.

If a person becomes physically dependent on a substance, their body will crave the drug in order to feel normal. This often leads people to abuse their prescription, and take higher doses than directed.

Body Mass Index (BMI)

Traces of benzodiazepines are stored in the body’s fatty tissues. If a person has a higher body mass index, they may have larger amounts of the drug in their system. However, Serax does not get stored in fatty tissue at the same level as many other benzodiazepines.

How To Get Serax (Oxazepam) Out Of Your System

Although Serax is not considered as addictive as other benzodiazepines like Xanax, this drug still has a high potential for abuse. The safest way to get Serax out of your system is through a medical detox program.

If a person stops taking Serax abruptly, it could lead to uncomfortable withdrawal symptoms.
The detoxification process can include withdrawal symptoms such as sleeplessness, anxiety, headaches, and irritability.

Getting off of Serax and other benzodiazepines can be a difficult process. Medically assisted detox programs provide physical and emotional support to those who are struggling with Serax abuse and addiction.

In a medical detox setting, doctors may suggest a tapering schedule. This means that the patient will be given decreasing amounts of the drug, until their body has had a chance to successfully detox.

Medical detox programs also use medication-assisted treatment, in order to help relieve the withdrawal symptoms associated with benzodiazepines like Serax.

Treatment For Serax (Oxazepam) Addiction

While some people take Serax without any problem, millions have been affected by benzodiazepine abuse and addiction.

This class of drugs is especially dangerous when mixed with opioids. More than 30 percent of opioid overdoses also involve benzodiazepine abuse.

If you or someone you love is struggling with Serax addiction, there is help available. Rehab centers across the U.S. exist to provide hope to those struggling with benzodiazepine abuse and addiction.

Many people who suffer from benzodiazepine addiction require the help of an inpatient rehab program. In inpatient treatment programs, patients are provided with detox therapies, medication-assisted treatment, addiction education, and counseling.

For more information on how long Serax (oxazepam) stays in your system, or to explore treatment options near you, reach out to one of our specialists today.

National Institute on Drug Abuse - Benzodiazepines and Opioids

Quest Diagnostics - Employer Drug Testing Solutions

National Institutes of Health, MedlinePlus - Oxazepam

U.S National Library of Medicine, National Institutes of Health - Benzodiazepine Pharmacology and Central Nervous System–Mediated Effects, Benzodiazepine use, misuse, and abuse: A review, Clinical pharmacokinetics of oxazepam and lorazepam

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