Alprazolam (Xanax) is a useful medication for certain mental health conditions. Xanax starts to work quickly, and it stays in the body long after the effects of one dose have worn off.

Doctors often prescribe Xanax for generalized anxiety disorder and panic disorder. It is one of the most common medications for these conditions, and it belongs to a class of drugs called benzodiazepines, or benzos.

Xanax works by increasing the effects of gamma-aminobutyric acid in the brain. This is a neurotransmitter that increases feelings of calmness.

This article looks at how long the effects of Xanax last, the timeline for withdrawal, and the various factors that affect this timing. It also describes when Xanax expires and how to safely dispose of old medication.

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People will usually notice the effects of Xanax within 1 hour.

Like many drugs, Xanax stays in the body long after a person stops feeling its effects.

Experts use a measurement called half-life to determine how long a drug stays in the body. A drug’s half-life is the amount of time that it takes for the body to eliminate half of it.

The half-life of Xanax is 8–16 hours in a healthy person, with a mean half-life of 11 hours. This is shorter than that of many other benzodiazepines.

The term “half-life” can be misleading, however. This is because it takes four to five half-lives for the body to completely eliminate a drug. This means that it may take an average of 44–55 hours, or about 2 days, for Xanax to leave the body.

In one study, researchers reported that they could detect Xanax in a person’s saliva for up to 2.5 days after their last dose.

The body absorbs Xanax quickly after a person takes it.

Peak levels in the blood occur 1–2 hours after taking a dose. However, the person will feel the effects before levels peak.

One study, which examined the effects of Xanax in 14 healthy people, found that participants felt the effects of the medication in under 1 hour, with an average onset time of 49 minutes.

The half-life of Xanax can vary from person to person. Several factors can affect how quickly the body processes it.

Some factors that may change the half-life of Xanax include:

  • being older
  • being of Asian descent
  • smoking
  • having obesity
  • having alcohol use disorder
  • having kidney problems
  • having liver problems

All of these factors can increase the time that it takes for the body to eliminate Xanax completely.

Which drugs can interfere with processing Xanax?

Some medications reduce the activity of CYP3A, which is a liver enzyme that helps process Xanax and eliminate it from the body. These medications are called CYP3A inhibitors.

Taking a CY3PA inhibitor with Xanax means that the body will take longer to process the drug. This can cause Xanax to build up in the blood and increase the risk of serious side effects.

A person should only take a CYP3A inhibitor with Xanax if a healthcare provider recommends it.

The following are some examples of CYP3A inhibitors:

  • birth control pills
  • azole antifungal agents, including ketoconazole and itraconazole, which can treat certain fungal infections
  • cimetidine, which reduces stomach acid and treats stomach ulcers, gastric reflux, and other digestive problems
  • selective serotonin reuptake inhibitor antidepressants, including fluvoxamine and fluoxetine

It is possible that Xanax could interact with some other medications and substances, including:

  • diltiazem
  • isoniazid
  • macrolide antibiotics, such as erythromycin and clarithromycin
  • grapefruit juice

Xanax and opioids

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Opioids are available by prescription.

Opioids are prescription pain relievers that block pain signals in the brain. Xanax can interact with opioids, and the interactions can be severe.

Opioids include:

  • fentanyl
  • morphine
  • codeine
  • oxycodone
  • hydrocodone

Taking Xanax and opioids together can cause a fatal overdose, in addition to severe interactions. This is because both opioids and Xanax slow a person’s breathing, and combining them may cause breathing to stop altogether.

If a person has been taking an opioid pain reliever, they should talk with their healthcare provider before taking Xanax. Likewise, anyone taking Xanax should speak with a doctor before taking an opioid.

People can become dependent on Xanax, even if they take it as prescribed. The risk of dependency increases if a person takes a higher dosage for a longer period.

When a person stops taking Xanax after their body has become used to receiving it, the lack of the drug can cause a range of physical and mental symptoms. These are called withdrawal symptoms.

Withdrawal symptoms for short acting benzodiazepines such as Xanax may begin 1–2 days after the person’s last dose. They may last for at least 2–4 weeks.

However, in 10–25% of long-term benzodiazepine users, withdrawal symptoms may last for 12 months or longer. This is called protracted withdrawal.

Xanax withdrawal can be dangerous. Symptoms of withdrawal include:

  • headaches
  • sweating
  • sensitivity to light or sound
  • muscle twitching
  • muscle cramps
  • insomnia and other sleep problems
  • blurred vision
  • diarrhea
  • difficulty thinking or concentrating
  • panic attacks
  • anxiety
  • seizures, including tonic-clonic seizures

A doctor can help a person gradually reduce their Xanax dosage. This is called tapering. Tapering can minimize the risk of serious withdrawal symptoms, including seizures.

Although withdrawal can be difficult, tapering is often effective. Two trials have shown that 71–93% of people were able to completely stop taking Xanax within 8 weeks by following a doctor-directed tapering schedule.

A bottle of Xanax should carry an expiration date and the date that the pharmacist filled the prescription.

Expiration dates indicate how long the drug is safe and effective to take. This date is based on when the manufacturer made the drug.

Taking an expired drug may no longer provide full benefits. Also, there is an additional risk of adverse effects.

Storing Xanax correctly helps ensure that the drug will remain effective until its expiration date. Store it in a dry place at room temperature, which is about 68–77°F (20–25°C).

Do not store Xanax in a bathroom, as moisture and humidity can cause the medication to break down sooner. Also, keep the bottle out of direct sunlight and out of the reach of children and pets. Make sure it stays in its original container.

Disposing of expired Xanax

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Store Xanax in a dry place at room temperature.

If Xanax has expired, it may not be effective or safe. Do not take expired Xanax before consulting a healthcare provider.

Because Xanax carries a high risk of dependency, it is important to dispose of expired or unwanted pills correctly.

In the United States, correct disposal means taking the medication to an authorized Drug Enforcement Administration (DEA) controlled substances disposal location. A person can find a local location using the DEA’s online system. There are also drug take-back days at select times of the year.

If a person cannot drop off their expired medication at an authorized location, they should follow the instructions for safe disposal in the trash from the Food and Drug Administration (FDA).

Xanax can be an effective treatment for anxiety and panic disorders if a person follows their doctor’s guidance.

Factors such as other medications and certain health conditions can affect how Xanax works and how long it stays in the body.

Anyone with an anxiety or panic disorder should work with their healthcare provider to develop a safe and effective treatment program.