Phentermine often leads to weight loss, but it’s not a miracle drug that instantly makes you slim, svelte and healthy. It's used in conjunction with an overall weight-loss plan that includes exercise and change of eating habits — and it's only used when you’ve exhausted all other avenues for losing weight. The drug also comes with an array of warnings and side effects, one of which is itchy skin.
Phentermine, technically known as Adipex-P, is a stimulant often prescribed to those that are obese or severely overweight to help control their weight, MayoClinic.com and RX List explain. The drug, which is similar to an amphetamine, works to diminish your appetite as well as making your stomach feel full longer than it would without the drug.
Itchy skin is one of the less-common side effects of phentermine. It can either be mildly uncomfortable or quite severe. Itchiness stems from an allergic reaction to the drug. Mild cases of itchy skin involve a general itchiness, while more severe cases sometimes include a skin rash or even hives.
If your skin breaks out into a rash, hives or the itchiness is particularly severe, Drugs.com suggests you see a doctor immediately. Your doctor can both treat the existing itchy skin condition as well as determine if you should continue to take the drug or perhaps switch to another medication or course of action for weight control.
Other Side Effects
Itchy skin is not the only side effect associated with phentermine. Some of the more common side effects include a dry mouth, dizziness, headache and stomach ache, constipation or diarrhea and a change in your sex drive or impotence. Because it is a stimulant, phentermine often leads to nervousness, restlessness, having a hard time sleeping or not being able to sleep at all. Some of the more severe side effects include a rapid heartbeat, tremors, difficulty breathing, fainting, tremors and allergic reactions, some as severe as the itchy hives, that include a swollen face, mouth or tongue.
Phentermine is potentially habit-forming, Drugs.com says, and is safest when you never exceed the prescribed dose. People with a history of alcohol or drug abuse are particularly at risk, as phentermine, too, has a high potential for abuse. Those that have a history of allergic reactions to other drugs, including stimulants, amphetamines, diet pills or even medications for colds, are at a higher risk of an allergic reaction to phentermine.