Frequent dieters may be familiar with the drug phentermine, a widely prescribed appetite suppressant. Although no longer marketed with fenfluramine as fen-phen because of potentially fatal heart complications, phentermine by itself still enjoys popularity among many dieters. Knowing how phentermine works and being familiar with its side effects can help you determine if this drug is right for you.
Phentermine assists dieters by suppressing their appetite and helping them to ingest fewer calories. It's basically very similar to an amphetamine, or "speed," in its effects upon the body. Phentermine works by stimulating both the hypothalamus, the area of the brain responsible for controlling hunger ,along with other functions, and the release of certain neurotransmitters. These special neurotransmitters, called catecholamines, cause your body to engage in a fight or flight response, which overpowers any hunger messages, thus helping you to eat less. So, phentermine uses both the central nervous system and the hypothalamus to help diminish appetite, and when you eat less, you lose weight. Because of its action upon these parts of the body, phentermine also typically makes the user feel more energetic and less drowsy.
Alas, the hunger suppressing effects of phentermine don't last forever. Typically, as people to continue to use this drug over weeks, they tend to build a tolerance to it, which basically means their body becomes so accustomed to the drug that it stops working as well. However, increasing doses dramatically may not be a good idea. Most doctors will only prescribe phentermine for short-term usage, usually 3 to 6 weeks, due to its addicting nature and high rate of side effects. Because phentermine affects the hypothalamus and nuerotransmitters, it also causes a number of related side effects, including nervousness, panic attacks, insomnia, and irritability, just to name a few. Also, since phentermine can be so addicting, most people need to taper off of it gradually, to avoid the risk of unpleasant withdrawal symptoms.