Phentermine and detection on drug test

Will Phentermine Show Up on the Drug Test? When Can This Become a Problem for You?

, reviewed by
 – Updated May 8, 2023
, reviewed by
 – Updated May 8, 2023
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Does Phentermine come up on a drug test? This is a fairly common question, and the answer is yes. Let’s explain why this is happening.

The Phentermine drug class belongs to Schedule IV, a list of drugs potential users may abuse. Or these drugs have a high risk of causing addiction. However, doctors note that Phentermine has a significantly lower risk than, for example, Alprazolam (Xanax). Moreover, several researchers argue that Phentermine is not addictive at all.

To quietly pass the drug test on Phentermine, you must understand the following.

Most urine tests for the presence of drugs and other similar substances are aimed at identifying a number of specific substances. Among them:

  • Heroin;
  • Cocaine;
  • Cannabis;
  • Prescription amphetamines and illegal Methamphetamine;
  • Prescription opiates and opioids;
  • Phencyclidine;
  • Phenobarbital;
  • benzodiazepines (Alprazolam, Lorazepam);
  • Methylenedioxymphetamine (MDMA), better known as Ecstasy;
  • LSD.

Phentermine and drug testing is a known problem. This drug is on the list of 10 drugs that could give false positive results for drugs.

Does Phentermine show up on a urine drug test?

Yes, that can happen. That’s because Phentermin’s structure is similar to amphetamines. And when testing urine for drugs, it could give a false positive for amphetamines or MDMA. This was confirmed by a study published in 2015.

How to pass a urine drug test for Phentermine?

If the urine test is positive, do not panic. You need to explain that you are taking Phentermine. Perhaps you will need to show a prescription for this drug. And then there will be a compelling reason to run another corroborating test, specifically on Phentermine, showing that this is the drug in your urine, not amphetamine, methamphetamine, or Ecstasy.

Does Phentermine show up on a mouth swab drug test?

Benzodiazepines and Phentermine are detected in urine tests. But tests for analysing samples of liquids from the mouth (smears) usually lack target indicators for their detection.

Can I get fired for taking Phentermine?

Phentermine is not banned, such as Methamphetamine. But it’s on Schedule IV, which means it’s a controlled drug. That is, it should be taken only if it was prescribed to you by a doctor who controls the treatment process. If you take Phentermine over the counter, your employer may consider it an illegal drug use and take appropriate action.

How long does Phentermine stay in your system?

Phentermine remains in the body for an average of 4 days. Half of the dose is excreted from the body approximately 20 hours after ingestion. However, this is a very individual indicator that depends on the person’s metabolism, age and weight.

How long does 15mg of Phentermine stay in your system?

The dose of 15 mg of Phentermine is eliminated from the body from 48 hours to 4 days. Take this into account if you have to do a drug test.

How to flush Phentermine out of your system?

To accelerate the removal of the drug from the body:

  • Drink more fluid;
  • Increase the intake of useful fats;
  • Increase physical activity. Devote at least 30-60 minutes to cardio training per day. This will speed up the metabolism and fat burning where Phentermine is stored;
  • Try to use supplements that remove harmful substances and slags. Consult a specialist about this.

Is Phentermine speed?

It is one of the most asked questions. The answer is: definitely not! Speed (slang name for methamphetamine) is a potent amphetamine that causes rapid addiction to the central nervous system stimulant. It is included in Schedule II, controlled by the U.S. Drug Enforcement Agency (DEA), and Phentermine is in Schedule IV, which is two degrees safer.

Methane and Phentermine

Given the popularity of this topic, we will consider it in more detail. So, is Phentermine amphetamine-like methane? No, no and no!

Phentermine is not an amphetamine. It can be called “amphetamine-like”. This means that it affects the same receptors and has a similar effect. As with amphetamine, a person’s appetite is suppressed, and more energy is released, which can even lead to insomnia.

However, the main difference with amphetamines is that much less dopamine is released when taking Phentermine. Its main targets are neurotransmitters such as norepinephrine and, to a lesser extent, serotonin. So it’s not addictive like methamphetamine or cocaine.

Is Phentermine a narcotic?

Only one country in the world recognized Phentermine as a drug. This is France. There, the substance is subject to additional restrictions specific to drugs.

In most countries of the world, Phentermine is approved for the treatment of overweight people. There it refers to controlled drugs and is available on prescription.

Is Phentermine an amphetamine?

No, Phentermine is not an amphetamine. They are in different categories on the list of controlled drugs, which is divided into five groups. Amphetamines are found in Section II, and Phentermine in Section IV.

How long do Phentermine effects last?

How long does Phentermine last in a day? To determine this, you need to divide the peak effect of the drug and its residual effect. In the first case, you do not want to eat completely; in the second – the desire to eat something manifests itself, but it is quite possible to fight it using willpower.

How long does it take for Phentermine to kick in? The main effect of Phentermine is appetite suppression. The drug’s effect in this area appears from one to two hours after taking it. The maximum concentration in the blood occurs after 3-3,5 hours.

How long does it take for Phentermine to work? The drug lasts up to 6-8 hours or even longer.

In addition to appetite suppression, short-term effects of Phentermine can manifest:

  • in euphoria;
  • in hyperactivity;
  • in the appearance of anxiety and irritability;
  • in chest pains.

How long does Phentermine detectable? Phentermine remains:

  • in the blood – for 24 hours or more;
  • in the urine – from one to four days;
  • in hair follicles – up to 30 days.

How long can you take Phentermine?

The Phentermine obesity treatment should not last longer than 12 weeks. This is the standard recommendation.

However, in a study dedicated to Phentermine long-term use, some people have taken Phentermine to lose weight for more than three months. There was no increased risk of heart disease or death. However, scientists have noted that additional clinical trials are required to ensure long-term safety.

Moreover, researchers at Wake Forest School of Medicine in Winston-Salem, North Carolina, have tested volunteers for this drug for 12 months or even 24 months. And all this time, weight loss continued! It is noted that the studies were under constant medical control.


In most countries (except France), Phentermine is not considered a drug and is approved for treating overweight patients.

However, standard urine tests for drugs may be positive for Phentermine, as it is structurally similar to amphetamines. (In the controlled drug classification, Phentermine is in group IV, while amphetamines and illegal methamphetamine are in group II).

In such cases, the person should be informed that he is taking the drug and ask for a special test on Phentermine.

However, over-the-counter Phentermine users may have problems with employment because it is illegal to use the drug without a prescription.

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