10 Reasons Why Your Doctor Won’t Give You A Phentermine Prescription

by Dr. Ahmed Zayed
Published on July 12, 2024
illustration of a doctor

Phentermine reigns supreme as **the ultimate slimming pill** not just in the US, but all around the globe. This schedule IV controlled drug has made waves by enabling countless individuals to shed pounds and sidestep the health nightmares linked with being overweight.

Perhaps you have heard people talking about this fantastic weight loss drug and you’re wondering how to get phentermine. Maybe even a close friend of yours or a family member has experienced success and served as living proof of what Phentermine is able to do when used as prescribed.

However, in many cases, your doctor may refuse to prescribe Phentermine, and you may be left wondering why. After all, Phentermine is only available with a doctor’s prescription, and buying anything that touted to be Phentermine online without a doctor’s prescription may put 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.

From above crop anonymous barefoot child in jeans standing on weigh scales on tiled floor of bathroom

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.

About Phentermine

This drug 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.

What Is The Purpose Of Phentermine?

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).

How Does Phentermine Work?

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.

This is why doctors generally provide patients access to a variety of weight loss services when giving them this prescription medication. Too many people expect the pill to work even when they continue to follow their usual routine. While Phentermine 37.5 mg is effective, it won’t work without a reduced-calorie diet. Patients are also usually only allowed to take the diet pills for a few weeks. When taking the diet pills for too long, may result in adverse effects. After a few weeks, the patient discontinues the use of the prescription medication. At this time, the patient should continue to follow a proper diet

The Potential Side-Effects of Phentermine

When using Phentermine to lose weight, patients are usually closely monitored by the healthcare provider. The patient is also advised to read the prescription label. This helps them determine risk factors, drug interactions, and other factors related to the medication. 

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. This is one of the most important reasons why a Phentermine prescription is needed before you can buy the pills. In most cases of misuse and abuse of Phentermine, patients have reported experiencing dizziness, headaches, muscle pain, dry mouth, palpitations, insomnia, digestive problems including nausea, vomiting, diarrhea and constipation, weight gain, hypertension, etc (2).

If the patient already experiences problems with their triglyceride and cholesterol levels, then they need to be careful when using this medication. These are risk factors for cardiovascular disease. When Phentermine affects blood pressure and other risk factors as well, the chances of experiencing serious side-effects increases. This may even lead to a need for emergency medical help. 


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). 

It is important to note that Phentermine can also affect your central nervous system, and not just cause changed in your blood pressure. This is why it is so important for a doctor to consider various factors before discussing drug administration with the patient. 

Some people may also take a double serving after a missed dose. In this case, a 37.5 mg serving suddenly becomes a 75 mg dose. This can cause more serious side-effects, as the doctor determines the lower 37.5 mg dose is the safest option for the patient. 

Phentermine Drug Interactions

Photo Medication Pills on White Plastic Container

When looking at side-effects of using Phentermine to lose weight, it is important to consider interactions. Some people are already using other diet pills or dietary supplements. In this case, Phentermine may interact with the other pills the patient is taking. A doctor can provide medical advice on this topic, and help the patient understand which drugs or supplements are the most effective option for them. 

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.

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.

Your BMI is not higher than 30

BMI stands for body mass index – a measurement of the body fat in a person. Your doctor will take your initial body mass index into consideration if you want a prescription for Phentermine. A healthy BMI falls between 18.5 and 24.9. If your BMI is higher than this, then you are overweight. 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).

You are struggling with hypertension

Woman in White T-shirt and Blue Denim Jeans Sitting on Brown Sofa

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 a case. When high blood pressure is the problem, drinking alcohol and eating foods high in sodium adds further risks. 

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 for the sole reason that this drug can enhance your glaucoma and worsen the symptoms.

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.

You have a medical history of substance abuse

Depth Photography of Blue and White Medication Pill

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. Later on, withdrawal symptoms occur when they stop using Phentermine. The risk is greater in people who have a medical history of substance abuse. It is only natural that the doctor will say no to using Phentermine in such cases.

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 – your doctor prescribes Phentermine for a period of 12 weeks. 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, follow your new habits of healthy eating and exercising regularly. If you continue with this plan, you will likely maintain your weight.

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. This accounts for any other medication and even vitamins, minerals, or supplements. Taking Phentermine when pregnant can cause problems with your growing baby. Researchers are still looking at how exactly Phentermine affects pregnancy. The medication can enter breast milk too. Pregnant and breastfeeding mothers should not use Phentermine until the end of their pregnancy and breastfeeding period.

You are suffering from anxiety 

Due to its stimulating effects, Phentermine can make you experience 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.

You have a diagnosed heart disease

Blue and White Digital Watch

If you have a diagnosed heart disease of some kind do not expect your doctor to give you a Phentermine prescription. And why is that, you ask? It is merely because Phentermine stimulates the parts in the central nervous system. These parts regulate your heart rate and blood pressure. Phentermine can easily lead to irregular heart rhythm. That is not all – it can quite easily increase the risk of heart attack and even congestive heart failure. Your condition can become worse if you use Phentermine with a cardiovascular condition. Your doctor will take factors like high cholesterol into account too. 

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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 though 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. When asking how to get phentermine and ask a Phentermine prescription, be sure to take all factors into account. 


(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/