Phentermine Withdrawal (Symptoms, timeframe, and weariness)

  • By: jacob foxx
  • Date: April 20, 2023
Phentermine Withdrawal

Phentermine is an FDA-controlled stimulant that is used for appetite suppression and increased energy. The FDA, however, closely monitors it due to its potential for abuse.

Phentermine works by stimulating the sympathetic nervous system, which results in an increased level of certain neurotransmitters.

It is crucial to note that withdrawal from phentermine can cause side effects, mainly due to changes in the state of neurotransmitters in the brain.

In this article, I’ll go over some of the most commonly reported phentermine withdrawal symptoms, why they happen, how long they last, and how you may deal with them.

In addition, I will inform you about the best phentermine substitute available.

Phentermine withdrawal symptoms

Phentermine, a weight loss pill present in the market since the 1950s, has gained significant popularity over the years.

Its success can be attributed to its classification as a Schedule IV controlled substance, making it a tested and trusted drug with over 3 million prescriptions in the United States alone.

As a central nervous system stimulant, phentermine’s potential for abuse is lower than that of Schedule II substances like amphetamine.

However, a recent study on obese patients who abruptly stopped taking phentermine showed possible physical or psychological withdrawal symptoms. 

The results of a recent study on phentermine have indicated that the abrupt cessation of this medication does not lead to any withdrawal symptoms, therefore suggesting a lack of addiction potential.

The study also found that the hallmark characteristic of substance dependence and abuse, ‘craving’, was not reported by any participant who took part in the trial.

Further analysis revealed that there were no significant differences between patients who stopped taking phentermine and those who did not take the medication at all.

However, significant differences were found between phentermine-treated and amphetamine-treated patients.

These findings provide useful insights into the effects of phentermine as a weight-loss medication and may lead to further exploration of its potential benefits.

In a scientific study, 269 obese patients were recruited to investigate the addiction potential of phentermine as a treatment for obesity.

The results of the study, published in the prestigious Nature journal, showed no signs of withdrawal craving, psychological dependence, or drug abuse even when the medication was used for extended periods of up to 21.5 years or at higher than recommended dosages.

This is a significant finding, as concerns regarding addiction to weight loss medication are valid.

However, user experience reported on medhelp suggests that side effects may be experienced when the prescription is stopped. 

Potential phentermine side effects after discontinuation

So, I’ve listed some common adverse effects that may occur after you stop using phentermine.

1. Low levels of energy

Phentermine is a medication that can provide energy for up to 14 hours by stimulating the sympathetic nervous system.

While it can be an effective tool in weight loss, continuous use of this drug may downregulate natural neurotransmitter systems that regulate energy.

This can lead to withdrawal fatigue once the prescription is stopped, as the body struggles to cope with the lack of artificial stimulation for these neurotransmitters.

2. Hyperphagia

Phentermine is a highly effective medication often prescribed to those struggling with obesity.

As an anorectic, it acts to reduce appetite, resulting in weight loss.

However, upon ceasing the prescription, many individuals experience an increase in appetite and cravings for carbohydrates, leading to hyperphagia or binge eating.

It is important to closely monitor one’s diet and exercise habits after discontinuing phentermine in order to mitigate the potential for weight gain.

3. A lack of activity Level

Many people who are coming off of phentermine experience the unfortunate side effect of low energy.

This can make even the simplest tasks feel like a burden, making individuals less likely to engage in physical activity.

Unfortunately, this lack of movement can lead to additional weight gain, potentially reversing the progress that was made while on the medication.

To make matters worse, the weight gain can be demotivating, causing individuals to feel overwhelmed and less committed to achieving their weight loss goals.

4. Mood swings

Discontinuing the use of phentermine can be a challenging task, as the brain needs time to stabilize its neurotransmitter release.

One of the most common psychological effects of phentermine withdrawal is a plethora of mood swings, including tension, irritability, depression, anxiety, paranoia, and emotional flatlining.

It is important to note that these symptoms can persist for some time, even after the medication has been discontinued.

5. Hypersomnia

Hypersomnia, the increased feeling of sleepiness, is a common drug withdrawal symptom that occurs in those coming off certain medications.

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Interestingly, the same neurotransmitters that play a role in keeping us awake also contribute to this feeling of excessive tiredness.

Specifically, dopamine and norepinephrine are known to promote wakefulness, but they can also trigger hypersomnia when their levels drop during withdrawal.

Moreover, dopamine has been found to affect the production and release of melatonin, the neurotransmitter that helps regulate sleep-wake cycles, which could also explain why hypersomnia occurs during withdrawal.

Studies have shed light on the complex interactions between these neurotransmitters and their impact on sleep, paving the way for more effective treatments of hypersomnia and other sleep-related disorders.

Phentermine withdrawal can cause low levels of norepinephrine, a neurotransmitter that plays a critical role in regulating attention and wakefulness.

Norepinephrine also helps to inhibit melanin production, a crucial function in skin tone.

Although there is no direct research that comprehensively explores the relationship between phentermine withdrawal and hypersomnia, recent studies have noted that patients who suffer from this condition after discontinuing phentermine often have lower levels of norepinephrine.

6. Lack of attention

The roles of neurotransmitters, dopamine and norepinephrine, in promoting attentiveness and alertness are crucial to our cognitive abilities.

However, when the use of phentermine is withdrawn, a decrease of these neurotransmitters may lead to inattentiveness.

Consequently, their role in maintaining attention and alertness cannot be overstated.

Notably, norepinephrine is also important for focus and memory retention, which means that a drop in its levels due to the withdrawal of phentermine can significantly impact our cognitive processes.

It is, therefore, critical to recognize the importance of these neurotransmitters in maintaining our cognitive functions to promote mental wellness.

7. Digestive issues and other symptoms

Discontinuing the use of phentermine can lead to a host of gastrointestinal symptoms, such as nausea, stomach cramps, abdominal pain, and even diarrhea or constipation.

Headaches and lightheadedness have also been reported. While some of these symptoms may be related to psychological states such as anxiety or depression, the research on phentermine withdrawal symptoms is still limited.

It’s essential to take these issues seriously and communicate with your healthcare provider if you experience any of these symptoms after discontinuing phentermine

How long do the withdrawal symptoms of phentermine last?

As with any medication, it is important to be aware of possible side effects and withdrawal symptoms associated with the use of phentermine.

The severity of side effects may vary, depending on factors such as the dosage, duration of use, and route of administration.

Intravenous and inhaled administration methods may result in higher plasma concentrations, while longer durations and higher doses may cause accumulation in the body.

Withdrawal symptoms can range anywhere from a few days to a few months after discontinuing use.

It is important to follow prescribed administration methods, which typically include taking the medication orally for 12 weeks or less, to minimize the risk of adverse effects. 

It is better to take medication via the mouth to ensure a stable and controlled release of the substance into the bloodstream.

However, if one decides to stop the medication, they may experience withdrawal symptoms that vary depending on the individual.

These symptoms can be most severe within the first four days of discontinuation and may last for several months, with low energy being a common symptom.

Physical withdrawal symptoms usually start about 36 hours after stopping the medication, peak within 6 to 7 days, and gradually taper off over time.

How do you handle phentermine withdrawal?

Phentermine, a popular weight-loss medication, works by stimulating the production of dopamine and norepinephrine in the brain.

These neurotransmitters are responsible for controlling our appetite, mood, and energy levels.

However, abruptly stopping the use of phentermine can cause withdrawal effects, as the brain readjusts to its natural levels of neurotransmitters. 

Now, read on to learn about methods to help you cope with phentermine withdrawal:

1. Cycle off safely

When it comes to cycling off phentermine, it’s important to do so safely to avoid any unwanted withdrawal effects.

Your doctor may recommend slowly reducing your dose, also known as “tapering.” This means your brain has time to adjust to any changes in neurotransmitter levels and stimulation that phentermine has provided.

Not only is tapering a safer way to come off of phentermine, but it can also increase the chances of long-term weight loss success. 

2. Maintain hydration and activity

Incorporating healthy habits such as staying hydrated and physically active while on phentermine can help boost weight loss progress and reduce the risk of unwanted side effects.

Medical professionals highly suggest at least eight glasses of water per day, which can act as an appetite suppressant, flush out toxins, and help prevent withdrawal symptoms.

By following a healthy routine that includes exercise and water consumption, patients can achieve their weight loss goals with phentermine effectively and safely. 

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Exercise is known to have numerous benefits, and recent studies have shown that it can improve mental health by increasing serotonin levels and decreasing appetite hormones like ghrelin.

These changes can counteract the psychological issues associated with anxiety and depression and prevent post-phentermine binge eating.

Exercise has been shown to regulate sleep cycles, leading to improved attentiveness throughout the day.

While there are many different types of exercise, resistance and aerobic exercise have been found to have unique effects on sleep.

For those looking to combat hypersomnia, aerobic exercise may be the best option, and activities such as dancing, swimming, or playing tennis provide excellent opportunities to get aerobic exercise on a daily basis.

3. Change to a Phentermine alternative

OTC stimulant-free diet pills may be the solution you’re seeking. Not only can they assist with appetite suppression, but they can also help you avoid common physical and psychological side effects such as hyperphagia, fatigue, and low mood.

Opting for a popular OTC weight loss pill not only guarantees improved physical health, but can also boost one’s mood and increase energy levels. PhenQ stands out as a potential OTC phentermine alternative.

Phentermine withdrawal Reddit

The user experience on Reddit may not always align with scientific evidence. However, in the case of phentermine, it seems to corroborate scientific findings.

Scientific evidence shows that the drug does not have addiction potential and does not cause severe withdrawal symptoms.

Despite this, Reddit user ‘Jooseyjintshire’ had a difficult time weaning off the drug after taking it for two years.

Her doctor had prescribed a half pill instead of a full one to taper the drug, but she still experienced extreme exhaustion, an excruciating headache behind her right eye, and stabbing pain that made her nauseous.

While this instance may be an outlier, it highlights the importance of individualized care and careful tapering when discontinuing medication.

Safer Alternative to Phentermine without withdrawal symptoms

Suffering from withdrawal symptoms after stopping the use of phentermine can be overwhelming, which is why turning to over-the-counter diet pills can be a helpful solution.

PhenQ, manufactured by Wolfson Berg, is a popular weight loss supplement with a track record of success.

With a 95% success rate and over 190,000 users who have benefited from its 5-in-1 formula, PhenQ has earned its status as a trusted weight loss supplement.

Not only does the supplement suppress appetite and burn fat, but it also prevents fat accumulation, boosts energy, and enhances mood.

Unlike phentermine, PhenQ does not come with serious side effects or withdrawal symptoms, making it a great alternative.

At $70 per bottle with a money-back guarantee available, PhenQ is a valuable investment in a healthier lifestyle.


Although phentermine withdrawal effects are not as severe as those associated with amphetamine withdrawal, it is still possible for users to experience a range of undesirable symptoms when ceasing the intake of this drug.

These shifts in body chemistry can be most commonly characterized by a loss of the drug’s therapeutic effects.

It is important to note that specific withdrawal side effects vary from one individual to another; however, common charges may include exhaustion, appetite disturbances, low activity levels, and difficulty concentrating.

To ensure successful withdrawal and avoid any prolonged difficulty associated with this process, it is strongly recommended that individuals slowly decrease their dosage under the guidance of a doctor, carefully following their prescription instructions.

I'm Jacob Foxx, a proud native of the outskirts of Chicago, Illinois. I was enamored with the expansive Star Trek universe and its promise of cutting-edge technology and space travel from a young age. This early fascination with science fiction sparked my imagination and laid the foundation for my writing career. Alongside my love for the cosmos, I developed a passion for fitness in my formative years.

This dual interest in the world of tomorrow and the pursuit of physical health has greatly informed my writing, allowing me to explore themes of human potential and the future of our species. As an author, I strive to blend these passions into compelling narratives that inspire readers to dream and to push their own boundaries.

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