Complete Guide To Phentermine

Obesity is a medical condition defined as the accumulation of body fat that causes general physiological imbalances. According to the World Health Organization, the obesity rates among the population have doubled since 1980. It is said that 600 million people around the world suffer from obesity. Among adults, 37% are overweight and about 13% are obese. More alarming is that 41 million children below 5 years old are already obese. With this rate, it is now known to be one of the greatest factors for mortality with an estimated morbidity of 300,000 deaths per year.

Not only tragic with its medical effects, today, there is a certain social stigma for overweight and obese people. This stigma is caused by specific standards that are set by members of the community. Through the years, this has caused several psychological disorders such as Anorexia Nervosa and Bulimia. As its rise reached an alarming rate, the fight to reduce or eliminate obesity is carried out by dieticians and health doctors. This has caused doctors to prescribe appetite suppressing drugs to initiate weight loss.

Though its safety is always questioned, more and more people have successful weight loss with the help of these drugs. One of the most clinically safe drugs that were released in the market is Phentermine.


Phentermine is a contraction of “phenyl-tertiary-butylamine”. It is a widely known anorectic. Anorectic drugs are psychostimulant drugs that suppress appetite that consequently lead to weight loss. It is considered a controlled drug in most countries and is medically used to treat obesity.


Phentermine first received an approval from the United States Food and Drug authority as an appetite suppressing drug in 1959. However, it was not sold in the market before the early 70s. It first came by brand names such as Lonamin and Adipex-P and was exclusively distributed by Medeva and Gate Pharmaceuticals.

Phentermine was then manufactured and marketed in combination with a known fat burning agent called fenfluramine. However, the FDA requested to take the drug off the market due to 24 reported cases of heart valve disease incidence among users in 1997. It was later proven that 30% of users had abnormal valve findings.

As of writing, phentermine is commonly sold as a pure drug or combined with other drugs at a small dosage. Phentermine is still available in most countries but is reduced to a controlled drug status as studies show that it is chemically similar to amphetamines. As a controlled drug, this can only be purchased as prescribed by a physician.


Phentermine is a combination drug derived from benzaldehyde and 2-nitropropane. As the complete byproduct of these two chemicals, it acts as a catalyst for the release of norepinephrine in the neurons. Norepinephrine is released in the Central Nervous System and the sympathetic nervous system responsible for overall thought process and perception. Phentermine's primary action in weight loss is the reduction of hunger perception which is a mechanism affected by the cognitive process. Outside the brain, it also releases norepinephrine and epinephrine causing cellular breakdown of stored fats.


Benzaldehyde and 2- nitropropane undergoes certain chemical changes that lead to the creation of phentermine. First, benzaldehyde and 2-nitropropane are cross-reacted in a variant of the Nitroaldol reaction. After this process, the Nitro group is reduced with hydrogen gas over Raney Nickel Catalyst. The hydroxyl group is then chlorinated with thionyl chloride to yield 2- amino-1- chloro-2-methyl-phenylpropane. Finally, this is reduced with hydrogen gas over a palladium on magnesium glycinate catalyst. The final product is then a complete phentermine.


Most common adverse effects of stimulant drugs affect the physical state of the user. As stimulant drugs directly affect the nervous system, it may also cause a breach in the brains homeostasis. Phentermine, as a stimulant drug, may affect functions that are controlled by the central nervous system and the sympathetic nervous system. These may include xerostomia (dry mouth), agitation, arrhythmia, tachycardia, hypertension, diarrhea, vomiting, headache, rash, urinary frequency, facial edema, unpleasant taste, urticaria, impotence, changes in libido and aortic regurgitation.

Some may also experience psychological effects such as nervousness, euphoria and agitation. Though users have reported several adverse effects at the same time, the effects of phentermine are generally well tolerated.


Phentermine use is generally contraindicated in those who:

  • Have known allergies or hypersensitivity to sympathomimetic amines.
  • Are taking another amphetamine drugs (e.g. Adderall) or have taken Aminoamine Oxidase Inhibitor (e.g. phenelzine) in the last 14 days.
  • Have hyperthyroidism, glaucoma, peptic ulcers, prostatic hypertrophy or epilepsy
  • Are receiving treatment with drugs that increase blood pressure.
  • Are diagnosed with heart disease or cerebrovascular disease.
  • Are pregnant, planning to become pregnant or breastfeeding.
  • Are receiving serotonergic medications such as tricyclic antidepressants.


Phentermine is a very potent stimulant drug. As the results are immediately visible to the user it can initiate addiction to the drug. With continued use, an occurrence of overdose is highly possible.

What are the warning signs of Phentermine overdose?

  • Difficulty in breathing and heart palpitations.
  • Hives or a breakout of allergic rashes
  • Dehydration
  • Severe migraine, mood swings and personality changes.

If you start feeling signs of an overdose, immediately seek emergency medical attention or call the Poison Help line.


Drugs similarly composed as amphetamines and stimulant drugs are addictive and habit forming. This may lead to drug overdose and can be very fatal. This drug should not be given to children below 16 years old. More so to avoid overdose, this drug must be taken in extreme caution.

Here are some tips to properly take the drug:

When you missed a dose, take the missed dose as soon as you remember. However, if it’s almost time for your next dose, do not take the drug. Do not take extra medicine to make up for a missed dose.

Avoid drinking alcohol as it may increase some side effects.

Be careful when you drive after taking phentermine. It may impair cognitive thinking and reactions.


Several studies about phentermine are conducted to prove the safety and efficacy of the drug. More so, some seek to prove the addiction potential associated with the use of this drug.

Most notable of which is the study entitled Long- term Phentermine Pharmacotherapy: An Investigation for Symptoms of Dependence, Cravings and Withdrawal sponsored by the Center for Weight Management in California.

In this study, it is proven that after 52 years of use there is no evidence to support that the drug has significant human addiction potential. However, since it is similar to amphetamines, it is believed that signs of addiction, dependency and withdrawal mimics those of amphetamines.

As for the questions on the safety of the drug use especially on the cardiovascular function of the body, a study sponsored by the Journal of Hypertension entitled Cardiovascular effects of phentermine and topiramate: a new drug combination for the treatment of obesity disproves that the use of phentermine can cause a significant increase in heart rate and blood pressure.

Weight loss is considered a treatment for reducing cardiovascular disease risk, however, with claims of cardiac irregularity with past users, the efficacy of phentermine is under constant fire. With this study, the data shows that there is no significant threat to the cardiovascular function of the user.


In some countries like the United States, phentermine is considered a controlled substance, therefore it is illegal to purchase it without prescription. Ordering a controlled substance is not necessarily illegal from another country that does not require prescription through online transactions. However, the possession and use of this substance in the United states without a valid prescription from a U.S doctor is illegal.

Legality is a concern due to a small percentage of people who have the propensity to abuse prescription drugs. However, most people have trouble getting phentermine because their healthcare professional found that they did not meet the strict qualifications for a prescription.

Reasons for failing to qualify for phentermine may include miscellaneous existing medical conditions such as high blood pressure; or the patient's BMI may simply not be high enough to justify such a serious medication.

For people who have heard of or enjoyed the benefits of prescription phentermine, and are unable to acquire a prescription, we created PhenterPro SR.

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