Exploring Diethylpropion vs Phentermine: Differences and Similarities

When it comes to weight management, people often find themselves navigating a maze of options. Two contenders that frequently emerge in this journey are Diethylpropion and Phentermine. People who want to lose weight can take medication known as appetite suppressants. While Diethylpropion and Phentermine share a common goal, they are distinct in their characteristics. 

Here, we explore the similarities and differences between these two weight-loss aids, learning about their mechanisms, side effects, and potential impact on a healthier and happier lifestyle. Learn more about Diethylpropion and Phentermine to make informed choices in weight loss.

Overview of Diethylpropion vs. Phentermine

Diethylpropion and Phentermine, classified as generic sympathomimetic prescription medications and central nervous system stimulants, play pivotal roles in weight management. Diethylpropion goes by the brand name Tenuate, while Phentermine is known as Adipex-P. Both fall under Schedule IV controlled substances, according to the U.S. Drug Enforcement Administration (DEA), underscoring their potential for abuse or dependence and necessitating controlled access. 

Designed exclusively for adults, these medications serve as tools for weight management, offering individuals options with nuanced differences in brand names, mechanisms, and regulatory classifications.

Diethylpropion vs. Phentermine: Conditions Treated

Conditions Treated:

  • Diethylpropion: Weight loss for significant overweight individuals.
  • Phentermine: Weight loss for significant overweight individuals.

Qualification Criteria:

  • Diethylpropion and Phentermine: Prescribed for obesity (BMI 30.0 or higher) or overweight individuals (BMI 25.0 to 29.9) with additional risk factors (hypertension, diabetes, hyperlipidemia).

Obesity Definition:

  • Diethylpropion and Phentermine: BMI of 30.0 or higher.

Classes of Obesity:

  • Diethylpropion and Phentermine: Class I (BMI 30 to 34.9), Class II (BMI 35 to 39.9), Class III (BMI 40 or higher).

Health Consequences of Obesity:                                                                                        

  • Diethylpropion and Phentermine: Increased risk of diabetes, stroke, heart disease, certain cancers; higher likelihood of mental health problems.

Overweight Definition:

  • Diethylpropion and Phentermine: BMI of 25.0 to 29.9.

Treatment Justification:

  • Diethylpropion and Phentermine: Being overweight alone is not enough to warrant prescription; additional risk factors are required (high blood pressure, diabetes, high cholesterol).

How Diethylpropion and Phentermine Work

Mechanism of Appetite Suppression


  • Functions as an appetite suppressant.
  • Targets neurotransmitters in the brain: serotonin, norepinephrine, and dopamine.


  • It also operates as an appetite suppressant.
  • Acts on specific neurotransmitters, including serotonin, norepinephrine, and dopamine.

Amphetamine-like Properties

  • Both Diethylpropion and Phentermine exhibit amphetamine-like characteristics.
  • They can inhibit or increase the release of targeted neurotransmitters, contributing to appetite control.

Uncertainty in Mechanism

  • Researchers must fully understand how central nervous system stimulants like Diethylpropion and Phentermine function.
  • The specific workings of the brain are not entirely clear.

Clinical Evidence

  • Clinical trials support the appetite-suppressant effects of Diethylpropion and Phentermine.
  • Elevated levels of norepinephrine, dopamine, and serotonin are associated with reduced feelings of hunger in individuals using these medications.

Diethylpropion and Phentermine Side Effects

Common Side Effects


  • Dizziness
  • Difficulty sleeping
  • Nausea
  • Diarrhea
  • Dry mouth
  • Irritability
  • Vomiting
  • Constipation


  • Dizziness
  • Headache
  • Dry mouth
  • Nausea
  • Increased heart rate
  • Increased blood pressure
  • Heart palpitations
  • Flushing
  • Sweating
  • Constipation
  • Diarrhea
  • Tremors
  • Nervousness
  • Restlessness
  • Irritability
  • Increased urination
  • Insomnia
  • Agitation
  • Altered libido

Serious Side Effects


  • Fast, irregular, or pounding heartbeat
  • Change in sexual ability/interest
  • Mental or mood changes (agitation, hallucinations, uncontrolled anger, nervousness, uncontrolled muscle movements)


  • Cardiovascular changes
  • Severe headache
  • Trouble speaking
  • Mental or mood changes (agitation, nervousness, uncontrolled anger, hallucinations, uncontrolled muscle movements)
  • Changes in libido
  • Weakness on one side of the body
  • Vision changes
  • Seizure

Life-Threatening Side Effects


  • Severe headache
  • Seizure
  • Vision changes such as blurred vision
  • Trouble speaking
  • Weakness on one side of the body


  • Cardiovascular changes
  • Severe headache
  • Trouble speaking
  • Mental or mood changes (agitation, nervousness, uncontrolled anger, hallucinations, uncontrolled muscle movements)
  • Changes in libido
  • Weakness on one side of the body
  • Vision changes
  • Seizure

Seek Immediate Medical Attention

  • If severe or life-threatening side effects occur, seek medical treatment promptly.
  • Continuous or worsening side effects should be discussed with a healthcare provider.
  • Be vigilant for potential drug interactions when using other medications concurrently.

Diethylpropion vs. Phentermine: Risks

Risks Associated with Diethylpropion and Phentermine

Both Diethylpropion and Phentermine, being central nervous system stimulants, pose risks and may have dangerous side effects, especially for individuals with certain medical conditions. Patients must provide a comprehensive medical history to their healthcare provider before considering either medication.

Shared Risks:

  • Abuse and Dependence:
    • Both medications have a risk of abuse and dependence.
    • Limited usage is recommended, typically for a few weeks.
  • Medical Conditions to be Disclosed:
    • Patients should communicate any relevant medical conditions to their doctor.

Conditions Making Safe Use Challenging for Both Medications:

  • Diabetes
  • High Blood Pressure:
    • Includes high blood pressure in the lungs.
  • Kidney Disease
  • Personal or Family History of Substance Abuse
  • Glaucoma
  • Heart Problems:
    • Fast or irregular heartbeat
    • Previous heart attack
    • Heart valve problems
  • Mental Health or Mood Problems:
    • Anxiety
    • Psychosis
    • Bipolar disorder
    • Schizophrenia

Additional Risks for Phentermine:

  • Stroke
  • Overactive Thyroid (Hyperthyroidism)
  • Seizures

Patient Advisory:

  • Patients with any of the mentioned medical conditions may face challenges using Diethylpropion or Phentermine safely.
  • Open communication with healthcare providers is vital for ensuring appropriate and safe medication usage.

Phentermine vs. Diethylpropion: Which Works Best?

A crucial aspect of examining Diethylpropion vs. Phentermine lies in their comparative effectiveness, as revealed by various studies. A specific 12-week study demonstrated that individuals treated with Phentermine experienced more weight loss than those treated with Diethylpropion. The noteworthy weight reduction primarily occurred in the final four weeks of the study. 

The Phentermine group exhibited significant reductions in blood pressure and resting heart rate, whereas the Diethylpropion group showed reductions exclusively in heart rate. 

Notably, the heart health improvements were attributed to weight loss rather than the medications directly. Diethylpropion and Phentermine offer valuable information to people seeking weight management choices by providing a comparative analysis of their effectiveness.