10 Reasons Why Your Doctor Does Not Want to Prescribe You Phentermine

by Dr. Ahmed Zayed
Published on December 26, 2018 and last updated for accuracy on April 4, 2019

Phentermine is one of the best weight loss drugs around the United States. It is the drug that has helped millions of patients so far get rid of their extra body pounds and all of the complications and potential health risks that come from obesity.

Perhaps you have heard people talking about this fantastic weight loss drug. Maybe even a close friend of yours or a family member have had their experience with Phentermine in the past, and they have served as sole proof of what Phentermine is able to do when used as prescribed.

But if you are reading this article, then chances are that your doctor has refused to prescribe Phentermine to support weight loss in your case, and you are wondering why that is. Yes, after all, Phentermine is only available with a doctor’s prescription and buying anything that resembles Phentermine online without a doctor’s prescription puts your life and health in danger.

Today, we are here to discuss the ten most common reasons why your doctor refuses to prescribe Phentermine to help you achieve weight loss.

Although we are sure that your doctor has already discussed his/her reason for not prescribing Phentermine in your case, it is always a good thing to do a little more investigating on your own. And that is why we are here today. In the following, you will find the ten most common reasons why doctors decide against Phentermine.

But first, let’s review what Phentermine is and what are its potential side-effects.

Phentermine – Know the Basic Facts About It

Phentermine first hit the market back in 1959 when it first appeared as a weight loss drug in a time when there were not many weight loss drugs available for purchase. Phentermine is a weight loss drug available only with a valid doctor’s prescription.

Phentermine is instructed to be used as a part of a doctor’s approved program that includes regular exercise and a reduced-calorie diet, as well as, behavior changes in order to achieve healthy weight loss. In fact, Phentermine is the number one used weight loss prescription drug to induce weight loss in cases of obesity and overweight (1).

What Phentermine does to induce weight loss is stimulating your nervous system in order to suppress your appetite and boost your energy levels. That way, you will feel less hungry and able to reduce your calorie intake as well as have the energy needed to engage in regular physical activity on a daily level.

A lot of patients tend to believe that they are using a magic pill when they use Phentermine and they do not have to reduce their calorie intake nor exercise on a regular level. That is where they go wrong. Unfortunately, in such cases, Phentermine is able to induce very little to no weight loss results.

The Potential Side-Effects of Phentermine

Any abuse or misuse of Phentermine is expected to lead to the occurrence of numerous side-effects as well as the development of an addiction. In most cases of misuse and abuse of Phentermine, patients have reported to experience dizziness, headaches, muscle pain, dry mouth, palpitations, insomnia, digestive problems including nausea, vomiting, diarrhea and constipation, weight gain, hypertension, etc (2).

Addiction is among the most dangerous side-effects caused by the abuse or misuse of Phentermine. Patients who have been using Phentermine longer than prescribed, and in much higher doses than recommended, have had their experience with withdrawal symptoms including depression, fatigue, weight gain, etc (3).

Ten Most Common Reasons Why Your Doctor Has Decided Against Phentermine in Your Case

Why are we telling you all this, you wonder? You have to understand that when your doctor has decided against using Phentermine in your case, he/she has probably a good reason, as you will understand in a little while.

There is always a good reason why some drugs are only sold with a doctor’s prescription, as these substances bring you closer to the potential side-effects and possible life-threatening risks. In the following, we will explain the ten most common reasons why doctors decide against using Phentermine to induce weight loss in cases of obesity and overweight.

  1. You are using certain medications at the moment – Phentermine as any other drug can interact with other medications and substances and cause harmful effects. That is why it is always important to keep your doctor updated on any new medications, substances, and supplements that you are taking at the moment. If you are, for example, taking Dopamine, Adderall, Ritalin, Marplan, Didrex, etc. at the moment, that might as well be the main reason why your doctor is refusing to prescribe you Phentermine.
  2. Your BMI is not higher than 30 – BMI stands for body mass index – a measurement of the body fat in a person. A healthy BMI is considered to be within 18.5 and 24.9. Anything above that is starting to be considered as a moderate to severe obesity. Phentermine is prescribed to treat obesity and overweight in cases in which the BMI of the patient is 30 or higher. If your doctor has measured your BMI and the results have shown that it is anything lower than 30, then your doctor will most probably refuse to prescribe you Phentermine (4).
  3. You are struggling with hypertension – As we mentioned before, Phentermine is acting by stimulating the nervous system which can lead to an increased heart rate and blood pressure. High blood pressure is an unfortunate common health issue among both men and women. And anyone who is already struggling with high blood pressure should not even think about taking Phentermine as well. In such cases, Phentermine can easily lead to extremely high blood pressure and put the life of the individual in grave danger. Your doctor is right to say no to prescribing Phentermine in such case.
  4. You have a diagnosed glaucoma – Glaucoma causes damage to the optical nerve, but how is that related to weight loss and the use of Phentermine? You see, by stimulating the right areas in the nervous system, Phentermine can induce dilatation of the pupil which will lead to an increase in intraocular pressure and aggravate glaucoma. If you have a diagnosed glaucoma, your doctor will probably refuse to prescribe your Phentermine on the sole reason that this drug can enhance your glaucoma and worsen the symptoms.
  5. You have hyperthyroidism – If you are suffering from an overly active thyroid gland – a condition known as hyperthyroidism, then your doctor will most probably refuse to prescribe you Phentermine to induce weight loss. It is because Phentermine increases the activity of the thyroid gland and leads to the increase of thyroid hormones. This will only make the hyperthyroidism symptoms worse and possibly even put the life of the individual in danger.
  6. You have a medical history of substance abuse – We already mentioned Phentermine being a highly addictive drug. Anyone who is abusing or misusing Phentermine is exposed to the great risk of suffering addiction and later, withdrawal symptoms as soon as they discontinue their use of Phentermine. Especially those who have had a medical history of substance abuse are exposed to this risk. It is only natural that the doctor will say no to using Phentermine in such cases.
  7. You have been using Phentermine for 12 weeks or longer – Phentermine is meant to be used only for a short period. To be more precise – Phentermine is prescribed for only 12 weeks and nothing more. Using Phentermine for longer than 12 weeks increases the risk of addiction and weight gain. If you have been using Phentermine for longer than 12 weeks, the chances are that your doctor will refuse to prescribe Phentermine once again, at least not right away. You will have to wait a couple of weeks, even months before you continue your use of Phentermine. Not to worry – in the meantime, by following your newly developed habits of healthy eating and exercising regularly, you are not bound to gain the lost weight back.
  8. You are currently pregnant and/or breastfeeding – If you are currently pregnant and/or breastfeeding, please consult your doctor before you proceed to use Phentermine or any other medication and even vitamins, minerals or supplements. Taking Phentermine during your pregnancy is considered to be potentially dangerous for your growing baby, although more scientific research needs to be done on the topic to explore the negative effects of Phentermine during pregnancy. It is also known that Phentermine is excreted in the breast milk, although more scientific research needs to be done to explore its effects on the infant. Pregnant and breastfeeding mothers are not supposed to be using Phentermine until the end of their pregnancy and breastfeeding period.
  9. You are suffering from anxiety – Due to its stimulating effects, Phentermine is known to cause restlessness, agitation, and anxiety. In such cases, taking Phentermine by individuals who are already struggling with anxiety might not be the best idea. Taking Phentermine in such cases can only make the anxiety problems bigger and possibly even endanger the individual’s life.
  10. You have a diagnosed heart disease – If you have a diagnosed heart disease of some kind do not expect your doctor to say yes to prescribing Phentermine. And why is that, you ask? It is merely because Phentermine stimulates the parts in the central nervous system that regulates your heart rate and blood pressure. Phentermine can easily lead to irregular heart rhythm, but that is not all – it can quite easily increase the risk of heart attack and even congestive heart failure. And if you are already suffering from some kind of heart disease at the moment, it is highly possible that using Phentermine at the same time will only make your condition worse. 


Phentermine is a great weight loss drug which when combined with a healthy diet and a regular exercise plan can easily lead to significant weight loss results. However, it is not for everybody.

Depending on your health status, your doctor might decide against using Phentermine to induce weight loss. Conditions such as pregnancy, breastfeeding, glaucoma, medical history of substance abuse and heart disease among many others that we have mentioned today make doctors decide against Phentermine.

After all, there are other great ways to lose weight and not put your life in danger and even through Phentermine is quite effective, your health is not something that you should risk. So think again – your doctor is probably right to decide against Phentermine and suggest other weight loss methods and you should not question his/her decision.


(1) https://www.rxlist.com/consumer_phentermine-hydrochloride/drugs-condition.htm
(2) https://www.rxlist.com/adipex-p-side-effects-drug-center.htm
(3) https://www.livestrong.com/article/448192-effects-of-phentermine-diet-pill-withdrawal/
(4) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4011567/

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