Sibutramine vs Phentermine: All Points Covered

Sibutramine vs Phentermine

Sibutramine and Phentermine both are medications that were used as weight loss medicines. Sibutramine has been withdrawn from the market due to safety concerns. Phentermine is still available and commonly prescribed for short-term weight management. Both Sibutramine and phentermine are not recommended for use together. Because Sibutramine can increase the side effects of Phentermine such as nervousness, anxiety, restlessness, and racing thoughts. Combining these drugs can also raise the risk of Serotonin Syndrome, an uncommon but serious illness that can cause confusion, hallucinations, seizures, dramatic blood pressure changes, an elevated heart rate, fever, heavy perspiration, and diarrhea.

In this blog, we will be discussing Sibutramine vs Phentermine and will cover all its grounds to help you understand the difference between them better.

Sibutramine vs Phentermine: Introduction

What is Sibutramine?

Recently, Sibutramine is taken off the market in Europe. It suppresses appetite and increases energy expenditure by inhibiting Serotonin and Noradrenaline reuptake. Sibutramine, marketed under the brand name Meridia among others, was a medication used to manage obesity by helping to suppress appetite and increase feelings of fullness. It acts on the brain’s appetite control centers by inhibiting the reuptake of certain neurotransmitters such as serotonin, norepinephrine, and dopamine. This led to increased satiety and reduced food intake. Sibutramine was typically prescribed for individuals who were unable to lose weight through diet and exercise alone.

What is Phentermine?

Phentermine is a medication approved by various health authorities for short-term weight management. It is a sympathomimetic amine that works by stimulating the release of Norepinephrine, a neurotransmitter that suppresses appetite. Phentermine primarily affects the Central Nervous System, reducing hunger and increasing the feeling of fullness.

Phentermine is often prescribed to individuals with obesity or those who are overweight and have related health conditions, such as high blood pressure, high cholesterol, or diabetes. It is typically recommended for short-term use due to its potential for dependence, tolerance, and side effects.

Why do we use Sibutramine and Phentermine?

We use Phentermine for short-term treatment for weight management in adults with a body mass index. Whereas we use Sibutramine for weight loss and maintenance of the weight loss. It is used in conjunction with a reduced-calorie diet and can assist with weight loss by altering neurotransmitters within the brain.

The side effects of Sibutramine and Phentermine:

What are the side effects of the Sibutramine?

Generally, the Sibutramine is well tolerated. There most common side effects of Sibutramine.

  • Constipation 
  • Headache
  • Dry mouth 
  • Abdominal pain 
  • Acne 
  • Rash 
  • Chest pain 
  • Joint pain
  • Anxiety 
  • Back pain 
  • Excitation 
  • Depression 
  • Dizziness 

There are some other important side effects of the Sibutramine namely:

  • Depression 
  • Psychosis 
  • Mania
  • Suicidal thoughts 
  • Suicide

What are the side effects of Phentermine?

There are some serious side effects of Phentermine:

Heart or lung disease: Dizziness, chest pain, leg pain or ankle swelling, feeling of heart racing or pounding, Inability to exercise, fatigue.

Severely high blood pressure: Severe headache, difficulty breathing, chest pain, blurry vision, confusion.

Low blood sugar: Feeling faint, shaking, sweating, nervous, anxious, confused, irritable, feeling very hungry.

Some Common side effects of Phentermine:

  • Dry mouth 
  • Headache 
  • Tremor 
  • Diarrhea 
  • Constipation 
  • High blood pressure
  • Fast heart rate 
  • Difficulty sleeping 

Other side effects:

  • Dizziness 
  • Restlessness 
  • Behavioral changes
  • Erectile Dysfunction 
  • Changes in sex drive 

What are the dosages of Sibutramine and Phentermine?

Typical dosages of Sibutramine:

One dose of Sibutramine per day is typically taken in the morning. One 10mg tablet per day is often the first dose for this therapy. There is a 15 mg dose increase possibility. The doctor will get the desired result within a few weeks. 60mg dose is presentable for studies. You can take sibutramine with or without food.

The typical dosing for Phentermine:


  • Adipex-P and generic phentermine capsules(37.5 mg strength): This typical dose is 37.5 mg by mouth once per day, either before breakfast or 1 to 2 hours after breakfast.
  • Generic Phentermine capsules (15mg and 30mg): The typical dose is 15mg by mouth once per day 2 hours after breakfast.


Orally disintegrating tablets (ODT):

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