Phentermine review

Phentermine was approved by the US FDA in the year 1959. Since then, Phentermine has been on the market in various forms, and brand names either used alone as Phentermine Hydrochloride or in combination with other medications such as Phentermine and Topiramate. In the this article, we will review Phentermine, including tPhentermine is a prescription weight loss medication or diet pill that is FDA approved in the US in the year 1959. It is one of the most popular prescription weight loss medication or diet pill as it is relatively safe, inexpensive and safe.

In this W8MD article on Phentermine Review, we will review the following:

  • Phentermine uses
  • Phentermine side effects
  • Phentermine overdose
  • Phentermine images
  • Phentermine Results
  • Dosage forms
    • Phentermine 15 mg
    • Phentermine 30 mg
    • Phentermine 37.5 mg
  • Phentermine FAQs
  • Phentermine Topiramate
  • Phentermine reviews
  • Phentermine interactions
  • Phentermine long term use
  • Phentermine brand names

Phentermine Uses

Let us start with the understanding what Phentermine is and how it is commonly used.Phentermine hydrochloride is one of the medicines approved by the United States Food and Drug Administration to assist people who are obese to lose weight in addition to a reduced calorie diet and increased physical activity.
Phentermine is a controlled substance although the addiction potential is very limited. In fact, in a recent study that looked at the addiction potential of Phentermine, it was determined that it has nill to very low potential for addiction.
Conclusion from the study on safety and addiction potential of Phentermine:
Phentermine abuse or psychological dependence (addiction) does not occur in patients treated with phentermine for obesity. Phentermine treatment does not induce phentermine drug craving, a hallmark sign of addiction. Amphetamine-like withdrawal does not occur upon abrupt treatment cessation even at doses much higher than commonly recommended and after treatment durations of up to 21 years.

For a medication that has been on the market for over 50 years, with proven results of assisting patients with obesity, Phentermine has remarkable track record which is why over 90% of all weight loss doctors prescribe Phentermine.

Availability of Phentermine

Phentermine HCL is available in three different doses in the United States.

Phentermine 15 mg

The Phentermine 15 mg dose is used in smaller individuals, elderly, those with medical pre-existing medical problems or as a starting dose before titrating to a higher dose.

Phentermine 30 mg

Phentermine 30 mg is used by most weight loss doctors as a starting dose for assisting with appetite control and to help with weight loss in addition to diet and exercise.

Phentermine 37.5 mg

By far, the Phentermine 37.5 mg is the most commonly used dose of Phentermine. Some physicians may start at this dose especially if you have previously been on Phentermine.

Brand names of Phentermine

  • Adipex-P
  • Lomaira
  • Fastin
  • Ionamin

Safety of Phentermine

Is Phentermine safe?

Phentermine is a relatively safe medication to take which is why most physicians that deal with obesity start with Phentermine. Although the internet might confuse you, in practice, as long as you monitor your heart rate, blood pressure and be under the care of physician while taking Phentermine, it is relatively safe medication.

Despite being on the market for over 50 years, there is not even a single published report of liver toxicity on the website which speaks for the relative safety of Phentermine.

Frequently asked questions about Phentermine

  • Is it dangerous to take phentermine?

Since Phentermine is an amphetamine, a prescription only medication, and a controlled substance, it has be prescribed by a trained and experienced physician that understands the proper use. It is dangerous to get Phentermine online or on the street without proper medication supervision. Your weight loss physician will monitor you on a regular basis while taking Phentermine including your heart rate, blood pressure, and other measures.

  • How is Phentermine taken?

Phentermine comes as tablets and extended-release capsules. It usually is taken as a single daily dose in the morning or three times a day 30 minutes before meals. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take phentermine exactly as directed.

  • What does phentermine do to the body?

Since Phentermine is an amphetamine that can increase your metabolism, it can cause more calories to be burnt at baseline. Since it is a stimulant, it has be used with caution in certain people with cardiovascular or psychiatric conditions. An experienced weight loss physician at W8MD can help you.

  • Can you drink caffeine while taking phentermine?

While you can drink small amount of coffee while taking Phentermine, you should exercise caution and limit usage of coffee or other caffeinated beverages to limit the stimulant effects.

  • What precautions should you take while on Phentermine?

Tell you doctor if you are allergic to phentermine, any other medications, or any of the ingredients in phentermine tablets. You should inform your phentermine doctor about all other medications, supplements and OTC substances you take so they can make sure it is OK for you to take Phentermine.
Tell your doctor if you take medication such as fluoxetine (Prozac), fluvoxamine (Luvox), guanethidine, insulin medications for weight loss and depression, paroxetine (Paxil), and sertraline (Zoloft). Also tell your doctor if you are taking monoamine oxidase (MAO) inhibitors such as isocarboxazid (Marplan), phenelzine (Nardil), selegiline (Eldepryl, Emsam, Zelapar) and tranylcypromine (Parnate), or if you have stopped taking one of these medications in the past 2 weeks.

  • How long does it take for phentermine to get out of your system?

The half life of Phentermine is about on an average about 23 hours although it can vary from 7 hours to 34 hours based on many factors including the Ph of the urine, alkaline urine make it last longer.

  • What are the common side effects of phentermine?

The more common side effects of phentermine can include:

  • bad taste in your mouth.
  • constipation.
  • diarrhea.
  • dry mouth.
  • headache.
  • vomiting.
  • Is Phentermine good for weight loss?

For most people, Phentermine is a good starting point either along or in combination with Topiramate as prescribed by a weight loss physician familiar with the concepts in obesity medicine.

  • What are the side effects of taking phentermine 37.5 mg?

Common side effects are altered taste, constipation, dry mucus membranes, palpitations, headache, vomiting etc.

  • Can phentermine get you high?

While it is a stimulant, it is rarely associated with getting people high. It has relatively low risk of addiction or habitation. See the results of this study on low risk of addiction – Phentermine addiction potential.

  • Does phentermine help you lose weight?

Yes. Phentermine is an effective appetite suppressant that can help one lose weight in addition to a reduced calorie diet and increased physical activity.

  • What time of day should you take phentermine?

Phentermine is usually taken in the morning so that it won’t affect your sleep. If it is prescribed more than once a day, you can take it in the afternoon or early evening. It is recommended to take the last dose of Phentermine at least 4-6 hours before sleep.

  • Can I drink wine while taking phentermine?

Caution is advised with alcoholic beverages while taking Phentermine. If you must have alcoholic beverages, try to limit to 1-2 drinks. Do not take Phentermine at the same time as alcoholic beverages.

  • Is it better to take phentermine on an empty stomach?

Yes, take Phentermine 30 minutes before meals.

  • Can phentermine cause you to fail a drug test?

If you are taking Phentermine, it will show up as amphetamines on urine drug test. However, since this is a prescription medication, all you have to do is prove that you are being prescribed it and the medical review officer (MRO) that handles the drug test will convert the test to negative before sending it back to the one who conducted the test such as employer.

  • Why Phentermine is a controlled substance?

The DEA determines which substances are controlled and according to them, Phentermine is a class IV controlled substance. On the DEA classification, class I are most habit forming and class V is the least.

  • Does phentermine cause constipation?

Phentermine causes dry mucus membranes and therefore can cause some constipation.

  • Can I just stop taking phentermine?

Although tapering is advised when taking or stopping Phentermine, sometimes physicians may ask you to stop without tapering. Talk to your physician on how to properly stop taking Phentermine.

  • Why is phentermine bad for your heart?

Phentermine is a stimulant similar to caffein. Other than it’s effect on slightly increased heart rate, and slight increase in blood pressure, Phentermine is generally considered safe. If you have pre-existing heart conditions that contra-indicate Phentermine, or recent heart attack, you should not take Phentermine.

  • Can phentermine cause hair loss?

In some people, Phentermine can lead to slight thinning of hair although this is rare.

  • Is it best to take phentermine on an empty stomach?

Yes. Take Phentermine before meals on an empty stomach.

  • What is the best prescription diet pill?

It depends. From an efficacy stand point, Phentermine with Topiramate is considered the most effective in a study that compared the various prescription appetite suppressants or diet pills.

  • What is the maximum amount of phentermine you can take?

It depends. Most weight loss doctors prescribe Phentermine 37.5 mg one time a day. Sometimes they may prescribe it up to three times a day.

  • Can I take levothyroxine with phentermine?


  • Can you overdose on Phentermine?

It is possible to overdose if you take more than recommended dose.

  • How many mg of phentermine can I take a day?

It is usually 15 mg, 30 mg or 37.5 mg, one to three times a day.

  • Does phentermine increase chance of pregnancy?

Not directly but indirectly as losing weight can increase chances of pregnancy.

  • Does phentermine make you lose weight or just suppress your appetite?


  • What Phentermine does to your body?

It increases your metabolism so you burn more calories.

  • How long does phentermine stay in your system?

The half life is about 25 hours or so.

  • Can you drink caffeine while taking phentermine?

Caution is advised but you can drink caffeine

  • Can phentermine cause heart attack?

Since it is a stimulant, there is a slight chance. However, most heart attacks are related atherosclerosis – a block in the arteries supplying blood to the heart, and Phentermine does not cause atherosclerosis.

  • Is Phentermine effective for weight loss?

It is very effective medication for weight loss for most patients although not everyone responds the same way.

  • What happens if I forget to take my phentermine?

You can skip a dose of Phentermine if you forgot or take it a bit later in the day as long as it is at least 6 hours prior to bed time.

  • What drugs interact with phentermine?

See the drug interaction section above – most psychiatric medications such as antidepressants are most commonly implicated.

  • What are the side effects of taking phentermine 37.5 mg?

See side effects section above

  • Is phentermine FDA approved?

Yes, in 1959.

  • What are the long term effects of taking phentermine?

Once Phentermine is out of system, which normally happens in about a week (or 7 half lives, phentermine has a half life of 25 hours), it would no longer have any effect.

  • What is the best time of day to take phentermine?


  • How long does it take for phentermine to take effect?

About 2 hours or so.

  • Can you get high from phentermine?

Rarely. In a recent study, Phentermine was found to be not addictive although the DEA still classifies it as a controlled substance.

  • Why does phentermine work so well?

It is an appetite suppressant and metabolic booster that increases you resting metabolic rate to help you burn more calories while resting.

  • Does phentermine increase heart rate?

Yes, as it increases you resting metabolic rate.

  • Why is topiramate used with phentermine?

There is synergy between Phentermine and Topiramate which is why this combination of Phentermine and Topiramate works so well. In fact, in a large study that compared the various weight loss medications or diet pills, the combination of Phentermine and Topiramate was found to be the most effective. See the study that compared diet pills.

  • Should I take my phentermine before or after breakfast?


  • How many times a day do you take phentermine?

1-3 times a day, although most people take it just once a day.

  • Does phentermine work for weight loss?

Yes, in combination with a reduced calorie diet and increased physical activity.

  • What is the best prescription diet pill?

It depends but the combination of Phentermine and Topiramate is considered the most effective.

What is the best diet pill on the market today?

Phentermine and Topiramate

Can phentermine affect thyroid?

Not usually

Can I lose weight on levothyroxine?

Yes. With reduced calorie diet, increased physical activity with or without appetite suppressant diet pills.

Phentermine is contraindicated in pregnancy.

Does phentermine make birth control less effective?

Slightly. Double protection using two methods of contraception is recommended.

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