The Athlete

Phentermine (Fastin, Adipex, Ionamin)

Phentermine is an anorectic drug in a similar class as amphetamines (speed). It stimulates the central nervous system, causing rapid heartbeat and an increase in blood pressure. This drug should only be taken for a short time by those who are extremely obese, and only under strict supervision of your doctor.

This drug is widely available over theĀ internet, but I would strongly caution anyone taking it without a doctor's recommendation. The long and short-term side effects can be extremely damaging. The risk factors must be carefully weighed before this drug is prescribed.

Side Effects

Cardiovascular: Palpitation (a strong heartbeat that you can feel), tachycardia (very rapid heartbeat), elevation of blood pressure.

Central Nervous System: overstimulation, restlessness, dizziness, insomnia (sleeplessness), tremor (shaking), headache, psychotic state, agitation (excessive restlessness), flushing, sweating, blurring of vision.

Gastrointestinal: Dryness of the mouth, diarrhea, constipation, nausea, stomach pain.

Endocrine: Impotence, changes in libido

Abuse and Dependence

Phentermine is classified as a Schedule III controlled substance. This means it has a high potential for abuse and addiction. Phentermine is related chemically and pharmacologically to the amphetamines. Amphetamines and related stimulant drugs have been extensively abused and many are now illegal.

Abuse of amphetamines and related drugs may be associated with intense psychological dependence and severe social dysfunction. There are, reports of patients who have increased the dosage to many times that recommended.

This drug must be used short-term only because long-term use can lead to psychosis, which is often clinically indistinguishable from schizophrenia.

Stopping the drug abruptly after high dosage administration, results in extreme fatigue and mental depression, as well as changes in sleep.


Tolerance is the body's ability to adjust to the drug and to need higher doses to achieve the same effect. Tolerance to the anorectic effect usually develops within a few weeks. When this occurs the recommended dose should not be exceeded in an attempt to increase the effect rather, the drug should be discontinued.


Phentermine should not be taken if:
* You have even mild hypertension (high blood pressure)
* You are insulin dependant
* You are taking any other stimulants
* You have a history of drug abuse
* You are normally a nervous or easily agitated person


Acute overdosage may manifest itself by the following signs and symptoms: unusual restlessness, confusion, belligerence, hallucinations and panic states. Fatigue and depression usually follow the central nervous system stimulation. Cardiovascular effects include arrhythmias, hypertension (high blood pressure), or hypotension (low blood pressure) and circulatory (blood vessels) collapse. Gastrointestinal symptoms include nausea, vomiting, diarrhea and abdominal cramps. Poisoning may result in convulsions, coma and death


Safe use in pregnancy has not been established. Until more information is available, women who are or may become pregnant unless, in the opinion of the physician, the potential benefits outweigh the possible hazards should not take Phentermine.

Usage in Children

Children under 12 should not take Phentermine.

Recommended Dosage

One tablet (30mg) taken once a day approximately 2 hours after breakfast. Taking phentermine later in the day is not recommended because of the possibility of resulting insomnia.

When properly used Phentermine can help the grossly obese lose weight, however it is a potent drug and shouldn't be used if you just have a few pounds to lose. As with all prescription weight loss drugs, have your doctor monitor your progress and should you experience any problems contact your doctor and stop the drug.

Fat-absorption inhibitors such as Xenical are seen to be less dangerous with milder side effects than the appetite supressants. They work by preventing your body from breaking down and absorbing fat eaten with your meals. This unabsorbed fat is eliminated in bowel movements. As with all medications, there are side effects but usually retsricted to gas discharges and bowel movements.

Information for the informed athlete: