Using Phentermine For Weight Loss For Those With Thyroid Conditions

Using Phentermine For Weight Loss For Those With Thyroid Conditions

About 39% of all adults over the world are overweight.


Obesity is estimated to affect about 13% of the worldwide adult population, with women being more likely to become obese than men, according to the latest statistics released by the World Health Organization1.


Due to the rising prevalence of obesity, several strategies have been implemented to assist in controlling this epidemic.


There are numerous complications that are directly contributed to by the presence of excess fat in the body.


This includes many life-threatening conditions, including diabetes and heart disease.


Phentermine is a pharmaceutical drug that was developed to act as a stimulant. The drug is able to possibly assist in reducing total body weight when combined with an appropriate dieting and exercise program.


While the drug is effective, those individuals who are experiencing issues with their Thyroid gland are often advised to be cautious about using Phentermine.


In this article, we examine the possibility of using Phentermine to assist with weight loss in cases where a person may be experiencing certain conditions that affect their Thyroid.


We will also consider cases where the combination may not be appropriate, and when a physician should be involved in the decision-making process.


What Is Phentermine And How Does It Work?

Phentermine is not a weight loss supplement that one can find at a local health store. This is a pharmaceutical drug that is developed using chemicals in order to treat obesity.


The drug is not prescribed to everyone. If a patient has only a small amount of excess weight, the physician is very unlikely to provide them with a prescription.


There are certain criteria that need to be met before a physician would provide the patient with a prescription for Phentermine.


The main reason why Phentermine is used as a treatment for weight loss is due to the appetite suppressant properties that the drug yields2.


In one journal entry3, researchers did extensive research in order to determine what the main driver or cause is behind the significant increase in obesity that has been observed over the last few years.


Following the research period, it was concluded that an energy intake that exceeded the daily energy expenditure seems to be the primary problem among the general population.


What this essentially means is that people seem to eat too much, especially when they are not exercising. This is what causes them to gain weight and become obese.


With the use of Phentermine, this issue can be avoided. The drug will reduce a person’s appetite, which makes the individual eat less food. Their energy intake decreases – and this helps to create a calorie deficit instead of a calorie surplus.


Phentermine is currently one of the most popular drugs that are used to help with the treatment of obesity. Statistics show that more than two million prescriptions for this medication are reached out to patients in the United States alone each year4.


How Is Phentermine Used For Weight Loss?

Phentermine is not a “magic drug” that will suddenly cause a person to lose weight. It is not something that a person can start taking and expect successful results without doing anything from their side in order to support their weight loss strategy.


For Phentermine to provide a person with effective results, it is crucial that the drug is combined with a weight loss plan. The medication needs to be accompanied by a diet program that ensures the person is able to achieve a calorie deficit – this is considered the only “true” way of losing weight.


Exercise also needs to be included in a weight loss program. Exercise does not only help to assist in burning excess calories but also ensures the person is able to achieve and maintain a calorie deficit. This means that they will be losing weight – as the person will be burning more calories than they are consuming on a day-to-day basis.


Dieting does not have to mean starvation, however. The person simply needs to calculate their daily energy expenditure and ensure they eat fewer calories than this calculation. Healthy foods should also be included in the diet.


There is no use in filling up the daily calorie intake by opting for takeaway foods that are drenched with saturated fats. Instead, healthy sources of protein, carbohydrates, and fats should be chosen.


Phentermine will act as an appetite suppressant in these cases. This will help the person better cope with their cravings. The person will feel fuller, and they will be less likely to overindulge during a meal or grab for a packet of chips or a chocolate bar between their meals.


Phentermine And Thyroid Issues

The development of one particular Thyroid issue, known as Hypothyroidism, is known to contribute to weight gain. The condition is relatively common.


Several studies have been performed in order to provide an overview of the possible prevalence. In one study, published in the Indian Journal of Endocrinology and Metabolism, researchers found that the epidemiology of Hypothyroidism may be as high as 10 %5.


The Thyroid gland plays a critical part in the regulation of metabolism. The adrenal glands work with the Thyroid in order to ensure metabolism works correctly. When a person develops Hypothyroidism, then their metabolism slows down. This is why one of the most common symptoms that a person would experience in the presence of Hypothyroidism is weight gain.


With this in mind, it might seem obvious to think that using Phentermine, which not only causes a suppression of appetite but also boosts metabolism, can be useful.


The only problem is that the underlying mechanisms that come into play here need to be considered. When we look at what happens in the background, it becomes clear that it might not be such a good idea.


To understand why this can be harmful, we need to look at how exactly Phentermine is able to boost your metabolism in the first place. According to scientists at the University of Florida in Gainesville, Phentermine primarily causes an increase in norepinephrine. This is a type of hormone that is more commonly known as adrenaline6.


The adrenal glands are responsible for producing and releasing norepinephrine hormones. Thus, with the use of Phentermine, excessive stress is placed on the adrenal glands. Now, this is also where the connection between the Thyroid and adrenal glands come into the picture.


Researchers have confirmed the connection between these glands7. When extra stress seems to be applied to the adrenal glands, then the stress ultimately has an impact on the function of the Thyroid gland.


Combining Levothyroxine And Phentermine

When a person is diagnosed with Hypothyroidism, the next step is usually for a doctor to prescribe them Levothyroxine. This is a type of synthetical drug that is similar to the Thyroxine, also known as T4, a hormone that the Thyroid gland produces. The idea behind the use of the medication is to restore optimal levels of Thyroxine in the body.


In turn, receptors that utilize the hormone can convert the synthetic substances introduced by Levothyroxine into the "active" type of Thyroid hormone – known as Triiodothyronine, or just T3.


It is generally advised to have the condition treated before complications develop – and when obesity is already a problem, a person may want to consider combining both Levothyroxine and Phentermine. This way, they would be treating their Thyroid problem and possibly experiencing a reduction in their body weight at the same time.


There are some risks that people should be aware of before combining these two drugs. In particular, there is a higher risk of experiencing certain side-effects when using both Phentermine and Levothyroxine.


Some of the most important risks that should be noted here include:


  • High blood pressure
  • Chest pain
  • Irregular heartbeat
  • Heart palpitations


People who have existing heart conditions are also advised to be wary of this particular combination.


How To Use Phentermine Safely With An Existing Thyroid Condition

Now that we have considered what exactly Phentermine is and why it is not always advisable to use it with an existing Thyroid condition, we are going to look at whether there is a safe way to go about using the drug.


The good news is that it is definitely possible to use Phentermine when suffering from a condition like Hypothyroidism. At the same time, however, there is some bad news – not everyone will be considered a good candidate here.


First of all, the risks need to be assessed. As described above, those who have been diagnosed with heart disease in the past are generally advised not to use Phentermine and Levothyroxine together. To avoid potential complications that may be caused by the reduction in Thyroid hormones caused by Hypothyroidism, in this case, it may be a better idea to opt for the use of Levothyroxine over Phentermine.


The important thing to note here is that Phentermine can provide effective results for a person with Hypothyroidism who is also obese. There are some initial steps that need to be taken, however, to make the entire process safer and to help prevent potential complications.


First, an official diagnosis for Hypothyroidism would be needed. The condition is known to cause symptoms that may include fatigue, hoarseness, muscle weakness, dry skin, and constipation8. These are all caused by the slowing of the metabolism.


Once diagnosed, Hypothyroidism needs to be the priority in terms of treatment and not obesity directly. A physician should first provide a patient with the appropriate medication to assist in the regulation of thyroid hormones in their bodies. Levothyroxine, as noted previously, is currently considered the preferred treatment method. The medication is able to provide an effective elevation of Thyroxine levels and, in turn, this would also lead to a higher concentration of Triiodothyronine in the patient’s body.


The process of balancing Thyroid hormone levels with Levothyroxine can take some time. This is important for the patient. The physician will provide the patient with an initial dosage of Levothyroxine, but there will often be a need for an adjustment in order to reach the right dose that would provide an adequate restoration of hormones in the body. The physician also needs to ensure the Levothyroxine dose is not too strong for the patient, as this may cause signs of hypertension.


Once Thyroid hormone levels have been balanced using Levothyroxine, and the right dose has been reached, it is generally advised that the patient waits about four weeks before they start using Phentermine. At this time, the use of Phentermine is not as likely to cause the person to experience an increased risk of side-effects. There will also be considerably less stress placed on the adrenal glands, which is the aim when trying to use Phentermine for the treatment of obesity when Hypothyroidism is present.


Thyroid hormones should be monitored frequently while using the combination of these drugs. Levothyroxine dosages should then be adjusted should changes in Thyroid hormone levels be noted.



Phentermine is a stimulant drug that helps to suppress appetite.


While generally considered a safe option for people with obesity who need to lose weight for health-related reasons, there are some precautions to consider before using the medication with a Thyroid condition.


Furthermore, interactions may occur when combining Phentermine with medication used to treat certain Thyroid conditions, such as Levothyroxine.


By following the right instructions, however, Phentermine can still play a useful part in helping a person with Hypothyroidism lose weight effectively.



1 Obesity and overweight. World Health Organization. 16 Feb 2018.


 2 Phentermine. PubChem.


3 Multiple Authors. Energy balance and obesity: what are the main drivers? Journal of Cancer Causes & Control. 17 Feb 2017.


4 Phentermine: Drug Usage Statistics, United States, 2006 – 2016.


5 A.G. Unnikrishnan, S. Kalra, R.K. Sahay, G. Bantwal, M. John, N. Tewari. Prevalence of Hypothyroidism in adults: An epidemiological study in eight cities of India. Indian Journal of Endocrinology and Metabolism. 2013.


6 N.E. Rowland, M. Marshall, J.D. Roth. Comparison of either norepinephrine-uptake inhibitors or Phentermine combined with serotonergic agents on food intake in rats. Journal of Psychopharmacology. Mar 2000.


7 K.N. Walter, E.J. Corwin, J. Ulbrecht, L.M. Demers, J.M. Bennett, C.A. Whetzel, L.C. Klein. Elevated Thyroid stimulating hormone is associated with elevated cortisol in healthy young men and women. BioMed Central: Thyroid Research. 30 Oct 2012.


8 Hypothyroidism (underactive Thyroid). Mayo Clinic.

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