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Phentermine Abuse: Treatment Options & Signs of Addiction

Phentermine is similar to amphetamine in chemical structure. It works in the same way to suppress appetite, but it has less potential for abuse than amphetamine.

While phentermine is not the most commonly abused stimulant drug, it is abused.

What Is Phentermine?

Phentermine is a medication that is used to aid weight loss for people who are overweight or obese, according to the U.S. National Library of Medicine.

It is a stimulant medication that can decrease appetite and increase metabolism. Phentermine is sold under the brand names Adipex-P, Obenix, and Ionamin.

Due to its stimulant properties, phentermine can be abused in the same way as other stimulant medications or drugs. It may be misused by those who have legitimate prescriptions for the medication, and it also has street value. It is sometimes sold in illicit marketplaces as a drug of abuse.

How Is It Used?

Phentermine is a widely prescribed drug, with more than four million prescriptions filled every year in the United States, according to the U.S. National Institutes of Health. It is typically used for a short time as a weight loss aid in conjunction with reduced-calorie diets as part of a comprehensive weight loss plan.

The medication comes in tablet form at 30 mg and as an extended-release capsule. When used as intended, it is taken either as a single dose in the morning or three times a day before meals. The recommended duration of the therapy is three to six weeks, but it could last up to 12 weeks in some cases.

Since phentermine is prescribed to patients who are trying to lose weight, it acts as an appetite suppressant. It can also boost energy to help in weight loss efforts.

It comes with some risks related to elevated heart rate.

It becomes less effective with ongoing use, so it is intended for short-term therapy only. Some patients can go off the medication for several months and then start another treatment round after a few months of being off of the drug. This helps to minimize risks to the patient.

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Can Phentermine Be Abused?

Phentermine does not result in psychological dependence and cravings when taken as prescribed, according to a study from the journal International Journal of Obesity.  Participants taking phentermine for treatment durations up to 21 years did not experience the kind of withdrawal symptoms associated with other amphetamine drugs, and they did not have cravings for the drug.

While the drug does not appear to result in psychological or physical dependency, there is the potential for abuse. Phentermine is still a stimulant drug, and some people may abuse it for those stimulating effects.

How Is It Abused?

how is it abused

Misusing phentermine involves taking the medication in any way other than intended, including taking more than the prescribed dose or ingesting it in alternative ways, such as crushing and snorting or smoking it.

People with eating disorders are at risk for abusing phentermine because of the drug’s weight loss effects. People with anorexia, binge eating disorder, or bulimia may misuse the drug to suppress appetite and lose weight even if they are not overweight or obese.

People who have a legitimate need for the drug and a prescription for it can also abuse the drug by taking more than prescribed. They may do this to amplify the appetite-suppressing effects or to achieve an energetic effect that can feel euphoric.

For people with obesity or those who have struggled with their weight for a long time, the energizing effect of phentermine can aid in weight loss, but it also can produce a reward response. If a person has struggled with low energy due to their weight problems, the feeling of having energy and being capable of doing more while eating less can be rewarding. This reinforces the drug abuse.

When they need to stop the medication due to the recommended parameters about the duration of use, they may go back to feeling as they did before, with lower energy and a stronger appetite. This change can result in a loss of the energizing benefits of the drug, causing people to feel compelled to get back on the drug to achieve those positive benefits.

The National Institute on Drug Abuse reports that more than 5 million American adults misused prescription stimulants in 2015 and 2016. About 400,000 people had stimulant use disorders.

Many people

Higher rates of stimulant use disorders are found among those with major depression, suicidal ideation, or substances abuse histories.

Those at risk for phentermine abuse include people who have eating disorders and those with a history of substance use disorders, particularly stimulant use disorders.

What Risks Are Associated With Phentermine?

Phentermine can cause side effects, some of which may be serious. The risk for serious side effects increases when the medication is abused.

NIDA reports that repeated misuse of prescription stimulants can result in psychosis, paranoia, and anger.

Some of the more common side effects from phentermine include the following:

  • Nervousness
  • Headaches
  • Dry mouth
  • Diarrhea
  • Vomiting
  • Sweating
  • Food aversions
  • Constipation
  • Increased blood pressure
  • Heart palpitations
  • Nausea
  • Insomnia
  • Restlessness
  • Dizziness
  • Shortness of breath
  • Chest pain
  • Edema

More serious side effects that are rare include atrial fibrillation, pulmonary hypertension, and acute psychosis. These side effects related to heart problems are the main reason that phentermine is only recommended for short-term use.

The risk of negative outcomes associated with the impact on the heart increases with prolonged use and abuse of the drug.

There are always cases in which individuals respond differently to medication than the majority of people. One recent case study published in Clinical Psychopharmacology and Neuroscience noted an incident in which a young female developed recurrent psychotic symptoms after taking phentermine.

While incidents like this have happened, they are rare. Most people who take phentermine do not experience these kinds of side effects.

How to Know if Someone Is Abusing Phentermine

Because one of the primary intended side effects of phentermine is weight loss, phentermine abuse can result in extreme weight loss. Someone who is on phentermine who loses an extreme amount of weight in a short amount of time may be abusing the drug.

Weight loss is not necessarily an indicator of abuse because that is the drug’s intended effect.  However, be cautious of excessive weight loss that occurs in a short time frame.

If someone was using phentermine as prescribed but then begins to obtain the drug illegally to continue using it past the recommended timeline of three to six weeks, this is a sign of abuse.

Some people may attempt to visit multiple doctors to obtain more than one prescription for phentermine. This may happen if an individual feels they need the drug to maintain their weight loss or are fearful that they will gain weight if the stop using the drug.

If someone who is not overweight or obese begins to use phentermine, it is a sign of abuse. Such use could be due to an eating disorder, or it could be associated with attempts to get high by taking the drug in excessive amounts or through alternative ingestion methods, such as snorting or smoking the drug.

It is possible to overdose on stimulants. Overdose on phentermine could result in irregular heartbeat leading to a heart attack, as well as hallucinations, breathing problems, or panic attacks.

What Happens During Withdrawal?

Phentermine does not appear to result in the same kind of withdrawal symptoms as other stimulant medications. However, if a person has been abusing phentermine, they may need to go through a tapered detox that includes treatment to address any potential distressful withdrawal symptoms.

People who have been abusing more than one drug will have a heightened risk of experiencing significant withdrawal symptoms.

Stimulant withdrawal typically results in symptoms that are the opposite of the effects of the drug.

  • Depression
  • Low energy
  • Lethargy
  • Increased appetite
  • Suicidal ideation

An individualized treatment plan to address potential withdrawal symptoms and provide ongoing support for those trying to get off prescription stimulants could include antidepressants as well as other medications to address physical symptoms like nausea, anxiety, or insomnia.

How Is Addiction Treated?

getting professional help

Addiction treatment is not just about withdrawing from medication. The addictive behaviors that accompany physiological dependency and cravings are rooted in deeper emotional issues.

Comprehensive addiction treatment includes appropriate medical protocols to withdraw from a drug of abuse safely, but it doesn’t end there. Educational groups, support networks, individual therapy, family counseling, and accountability systems are all part of the addiction recovery process.

In the case of stimulant abuse, addiction therapy will include looking at the underlying beliefs and core emotional struggles that contribute to the addictive behaviors. For example, if a person with an eating disorder has been abusing phentermine to lose weight, a more comprehensive treatment plan that includes addressing the eating disorder must be included to treat the addictive behaviors fully.

Can You Fully Recover?

Full addiction recovery is possible after phentermine abuse. 

Phentermine does not typically cause the kind of long-term cravings for the drug that can trigger multiple relapses for most people. However, many people change their drugs of choice and experiment with different drugs of abuse even after completing treatment. Thus, ongoing treatment is required.

Full recovery from any addiction can be accomplished with a good clinical treatment plan and a supportive recovery network.


(February 2014). Addiction potential of phentermine prescribed during long-term treatment of obesity. International Journal of Obesity. from

Behavioral Health Treatment Services Locator. Substance Abuse and Mental Health Services Administration. from from

(April 2018). Five Million American adults misusing prescription stimulants. National Institute on Drug Abuse. from

(February 2017). Intentional vs. Unintentional Overdose Deaths. National Institute on Drug Abuse. from

(January 2019). Phentermine. U.S. National Library of Medicine. from

(October 2018). Phentermine. National Institutes of Health. from

(June 2018). Prescription Stimulants. National Institute on Drug Abuse. from

(February 2019). Recurrent Psychosis after Phentermine Administration in a Young Female: A Case Report. Clinical Psychopharmacology and Neuroscience. from

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