Side Effects of Fastin Diet Pills

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Fastin is a diet pill containing phentermine hydrochloride. Fastin requires a doctor’s prescription and is not available over the counter. According to, phentermine suppresses the appetite. Its mechanism of action is unknown, but it seems to decrease appetite by acting on centers in the brain that control appetite. In addition, it is similar to amphetamine and stimulates the nervous system, elevating blood pressure, and increasing your heart rate.

Allergic Reactions

As with any other drug, phentermine may cause an allergic reaction. When taking phentermine watch for signs of allergic reactions such as rashes or difficulty breathing. If symptoms occur, stop taking the medication immediately and tell your doctor about it.

Nervous System Reactions

Phentermine may cause side effects due to its action on the fight or flight response. According to, a phentermine information website, side effects can include a bad taste in your mouth, difficulty in sleeping, dry mouth, dizziness, restlessness and constipation. If you experience symptoms like insomnia, nervousness and overactive reflexes, stop activities that require concentration such as driving and operating machines. The side effects of phentermine vary according to the gender and age of the user. Some people also experience circulatory or cardiac effects such as hypertension and arrhythmias. Feelings of euphoria may also be experienced. Sexually related side effects of phentermine such as decreased sex drive or impotence are also possible.

Severe Side Effects

Fastin has been known to cause serious side effects in some users. According to, significant side effects may include overstimulation, restlessness, insomnia, dysphoria, tremor, headache and possible psychotic episodes at normal doses. Side effects such as rashes, hives, difficulty breathing and a tight feeling in your chest need immediate medical attention. Other severe side effects include swollen lips, tongue or face as well as unusual behavior, fast heartbeat, palpitations, shaking or swollen feet or legs. All of these require medical attention.


Because Fastin is closely related to the amphetamine family of drugs, overuse may lead to addiction. Withdrawal symptoms such as fatigue, depression and insomnia may be experienced. Although the risk of addiction is low it should be a concern if you have had previous addiction problems especially to methamphetamine. In addition, if you have diabetes and require insulin you may have to adjust your insulin dose.