Phentermine

• Phentermine hydrochloride (HCL), typically referred to as simply phentermine, is a prescription drug for dietary weight loss. The drug is available in pill form and is typically prescribed to obese individuals for short-term use. Though the pill works as an appetite suppressant, doctors recommend that phentermine be used in combination with other more natural weight-loss solutions, such as diet and exercise.
  
  

The Science

• Phentermine is a member of the sympathomimetic family of drugs. These appetite suppressants work by stimulating the hypothalamus, a gland found in the brain. The hypothalamus is responsible for regulating a number of autonomic nervous system functions, including appetite.
  
  When phentermine enters the body, it triggers specific neurotransmitters (known as catecholamines) that send a signal to the hypothalamus to curb hunger. Specific neurotransmitters involved include dopamine, epinephrine and norepinephrine.
  
  

Phentermine Tolerance

• Phentermine is partly prescribed for short-term use because patients sometimes build up a tolerance to the drug. This tolerance can occur in as quickly as a few weeks. Once tolerance sets in, phentermine's ability to trigger neurotransmitters is greatly reduced. As a result, the hypothalamus remains unaffected and hunger continues. Again, phentermine is intended as a short-term solution for easing the transition into a reduced-calorie diet and/or more physical lifestyle.