A Possible Link Between Phentermine And Heart Failure: What You Need To Know

Recent observations suggest a possible link between phentermine and heart failure, causing concern in medical circles. While such cases are rare, there have been reports of valvular heart disease in people who have used phentermine. The drug has also been implicated in the development of pulmonary hypertension, a serious condition characterised by increased blood pressure in the pulmonary arteries.

Valvular heart disease is a condition characterised by damage to one or more of the heart’s valves, which are essential for regulating blood flow in the cardiovascular system.

In addition to its association with valvular heart disease, phentermine poses another significant risk in the form of pulmonary hypertension, a condition in which the pulmonary arteries become overloaded due to increased blood pressure.

Because of these potential risks, people with pre-existing cardiovascular or pulmonary conditions are advised not to use phentermine.

This article examines the emerging link between phentermine and heart failure and identifies the population groups that should avoid its use. It also examines alternative interventions for obesity, taking into account the risks posed by phentermine.

What Is Phentermine?

Classified as a central nervous system stimulant, phentermine is a powerful weight management tool that suppresses appetite. Its introduction to the pharmaceutical market dates back to 1959, initially as part of a combination therapy for obesity. But it wasn’t until the 1980s that researchers discovered its synergistic potential when combined with fenfluramine, another appetite suppressant.

The combination, popularly known as ‘fen-phen’, showed a combined effect that was greater than the sum of its parts. Despite its promising results in the fight against obesity, the tandem came under scrutiny due to emerging links with pulmonary hypertension and valvular heart disease. Subsequent research raised similar concerns about fenfluramine as a single drug.

As a result of these findings, the Food and Drug Administration (FDA) intervened and quickly banned fenfluramine in 1997 because of the health risks associated with it. However, phentermine retained FDA approval for short-term use in weight management programmes. So while fenfluramine fell out of favour, phentermine remained a therapeutic option, albeit under strict regulatory control.

Is Phentermine Safe?

Recent research highlights a possible link between phentermine and pulmonary hypertension, a rare but serious condition. Symptoms such as breathlessness, chest discomfort, fainting, or leg swelling should prompt immediate discontinuation of phentermine use.

In addition to the risk of pulmonary hypertension and valvular heart disease, there are other health risks associated with phentermine:

  • Development of tolerance: Users may require increased doses to achieve desired effects, exceeding safe limits.
  • Potential for abuse and dependence: Due to its chemical similarity to amphetamine, phentermine carries a risk of dependence.
  • Impairment of cognitive function: There is a risk of reduced ability to operate machinery or drive safely.
  • Adverse interactions with alcohol: Consumption of alcoholic beverages with phentermine is not advised.
  • Contraindications with certain drugs: Concomitant use with other weight loss drugs or SSRIs is not recommended.

While the FDA has approved phentermine for short-term use, an older study from 2014 highlights the need for further clinical trials to determine its long-term safety, especially for durations longer than six months. Data on cardiovascular effects after use for more than a year remains notably scarce.

The Potential Impact Of Phentermine On Heart Health

Phentermine And Hearth Failure

Phentermine, whether prescribed alone or as part of a combination medication with topiramate, raises pertinent questions about its effect on cardiovascular well-being.

Phentermine Alone

While phentermine monotherapy remains a prescription option for weight management, concerns remain about its association with valvular heart disease. Although rare, there have been documented cases of people taking phentermine developing this condition, prompting a closer look at its cardiovascular effects.

Combination Therapy With Phentermine And Topiramate

When phentermine is used in combination with topiramate, a different set of considerations arise. In particular, this combination therapy has been observed to increase resting heart rate by up to 20 beats per minute (bpm). Such an increase, if sustained, could potentially increase the risk profile for individuals, particularly those predisposed to cardiovascular problems.

Interestingly, despite this notable effect on heart rate, the product labelling does not explicitly address the risk of valvular heart disease associated with the combined formulation, as seen with phentermine alone.

Furthermore, the synergistic effects of phentermine and topiramate go beyond just cardiovascular effects, as the combination has been found to cause significant interactions with other drugs that affect the heart. For example, concomitant use with selective serotonin reuptake inhibitors (SSRIs) can lead to serotonin syndrome, which poses a significant risk to patients.

Given these complexities, clinicians must exercise caution when prescribing phentermine, either as monotherapy or in combination with topiramate, and ensure that individual patient profiles and potential cardiac risks are carefully considered.

Risk Factors: Identifying Individuals Prone To Cardiovascular Complications

Individuals with pre-existing cardiovascular conditions have an increased susceptibility to adverse cardiac effects associated with phentermine use, necessitating cautious exclusion from its use. This population includes those with:

  • Coronary artery disease: Individuals with coronary artery disease, a condition characterised by narrowing or blockage of the heart’s blood vessels, are considered unsuitable candidates for phentermine therapy due to the increased risk of worsening cardiac complications.
  • History of stroke: Patients with a history of stroke, indicating cerebrovascular complications, warrant strict avoidance of phentermine to reduce the potential risk of recurrent cardiovascular events.
  • Uncontrolled hypertension: Individuals with uncontrolled hypertension, characterised by persistently elevated blood pressure levels, are considered unsuitable for phentermine therapy due to the increased risk of precipitating hypertensive crises and associated cardiovascular sequelae.
  • Cardiac arrhythmias: Individuals with cardiac arrhythmias, which include irregular heart rhythms, should avoid phentermine use to prevent potential exacerbation of underlying cardiac arrhythmias.
  • Congestive heart failure: Patients with congestive heart failure, characterised by the inability of the heart to pump blood efficiently, are at increased risk and are advised not to take phentermine.

Given the precarious nature of these cardiac conditions and their potential interaction with phentermine, healthcare providers must exercise careful discretion in assessing patient candidacy for the drug, prioritising individualised risk stratification to protect against adverse cardiovascular outcomes.

What Are The Symptoms Of Heart Failure?

Heart failure is characterised by a range of symptoms that indicate that the heart is unable to pump enough blood to meet the body’s needs. These symptoms can vary in onset and intensity, developing gradually in some people and suddenly in others. Common signs of heart failure include:

  • Breathlessness, particularly with physical exertion or when lying down
  • Fatigue and general weakness, often persistent and debilitating
  • Oedema, characterised by swelling in the lower extremities, including the legs, ankles and feet
  • Arrhythmia, characterised by a fast or irregular heartbeat
  • Decreased exercise tolerance, reflecting the heart’s reduced ability to sustain physical activity
  • etc.

Exploring Alternatives To Phentermine

In the search for weight management solutions, several alternatives to phentermine have emerged, each with its own set of benefits and considerations.

Other Anti-Obesity Drugs

In addition to phentermine, there is a spectrum of anti-obesity drugs, each with different mechanisms of action and associated risks:

  • Orlistat (Xenical): Reduces fat absorption
  • Naltrexone-bupropion (Contrave): Suppresses appetite or makes you feel full
  • Liraglutide (Saxenda) or semaglutide (Wegovy): Mimics hormones involved in appetite regulation
  • Setmelanotide (Mcivree): May reduce appetite, increase satiety and increase metabolism

However, it’s important to be aware of the potential side effects and risks associated with these alternatives. Prescribing the appropriate medication and dosage requires careful consideration by a healthcare provider.

Mediterranean Diet

In contrast to fad diets, which are often considered to be unsustainable and unhealthy, the Mediterranean diet is a balanced and nutritious diet that promotes sustained weight loss. Emphasising the consumption of nutrient-dense, fibre-rich foods such as fruits, vegetables, nuts and whole grains, coupled with the inclusion of olive oil and oily fish, this dietary approach has attracted attention for its long-term viability. Earlier research in 2010 involving 10,376 participants highlighted its potential to curb age-related weight gain, in part due to its palatability and adherence.


Acupuncture, an alternative therapeutic approach, involves inserting thin needles into specific pressure points on the body. A comprehensive 2018 review, which included 21 studies and 1,389 participants, looked at the effectiveness of acupuncture for obesity. While the findings suggest it is a safe and effective intervention, further longitudinal research is needed to validate its long-term effects.

Weight Loss Surgery

Reserved for individuals with a body mass index (BMI) of 35 or higher, weight loss surgery is a viable option to facilitate substantial weight loss by altering the digestive system. Bariatric surgery, a common approach, involves dividing the stomach to create a smaller upper pouch. While the results are promising, both short-term side effects and long-term risks underscore the importance of careful patient selection and follow-up. When conventional interventions prove ineffective, weight-loss surgery may be considered, but requires adherence to a sustainable lifestyle programme to optimise outcomes.

Risks of buying phentermine without a prescription

Buying phentermine without a doctor’s prescription carries significant risks. Without medical supervision, there is a risk of side effects and interactions with other medications or diseases. In addition, counterfeit or substandard products can seriously endanger your health. If you want to buy phentermine over the counter, you can find some offers on jpost or onlymyhealth.


In rare cases, reports have suggested a possible link between phentermine use and the development of valvular heart disease, raising concerns about its association with heart failure. It has also been implicated in the development of pulmonary hypertension, a potentially fatal condition.

In some cases, doctors may choose to use a combination of phentermine and topiramate. However, it’s important to note that this combination has been associated with increased heart rate.

People with any form of cardiovascular disease are advised not to use phentermine. In addition, prior to starting phentermine therapy, patients should fully disclose their current medication and supplement regimen to their healthcare provider to reduce the risk of adverse interactions.


  • National Center for Biotechnology Information. “Topiramate and Phentermine.” NCBI Bookshelf, NIH, Link.
  • PubChem. “Phentermine.” National Center for Biotechnology Information, Link.
  • National Center for Biotechnology Information. “Long-term Drug Treatment for Obesity: A Systematic and Clinical Review.” PubMed Central, PMC3928674, Link.
  • National Center for Biotechnology Information. “Acupuncture on Obesity: Clinical Evidence and Possible Neuroendocrine Mechanisms.” PubMed Central, PMC6022277, Link.
Oliver Bartzsch is an experienced medical professional with over 15 years of professional experience. With a passion for medicine, fitness, and personal growth, he is always willing to challenge himself to accomplish tasks and especially to provide accurate medical information to people. Oliver is a long-time medical editor for multiple sites. With more than 10 years of medical writing experience, he has completed over 350 projects with both individual and corporate clients.


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