Imagine you’re struggling to lose weight. You’ve tried diet and exercise, but nothing seems to work. Your doctor diagnoses you with hypothyroidism and prescribes levothyroxine. As you start taking the medication, you notice a slight improvement in your weight, but you’re still not seeing the results you want. Desperate for a solution, you consider adding an Adipex-P or Lomaira to your routine. You’ve heard it can be a powerful appetite suppressant, but you’re unsure if it’s safe to combine with your thyroid medication. You don’t even know if your doctor will prescribe it. No doubt this can be quite frustrating. But, it doesn’t really have to be.
If this is exactly your situation, just know that you’re not alone. There are many discussion threads on this particular issue on various QnA platforms and online forums such as Quora and Reddit, indicating that many other people do indeed share the same experience. For this reason, this article is meant to explain the complexity of the simultaneous dosing of phentermine and levothyroxine. In this article, we will also see a few tips for how to take these medications properly.
How do phentermine and levothyroxine work?
Phentermine
Phentermine is a stimulant similar to amphetamine, which is present in drugs like Adderall. As an anorectic drug, phentermine affects the central nervous system, acting as an appetite suppressant. The drug specifically stimulates the release of norepinephrine in the brain, which increases heart rate and blood pressure, reduces appetite, and can help with weight loss. Phentermine is generally used short-term, over a period of a few weeks, as part of a comprehensive weight reduction program that includes exercise, behavioral changes, and calorie restriction. The usual dose is once daily, taken either before breakfast or 1-2 hours after breakfast.
Levothyroxine
Levothyroxine is a synthetic form of thyroxine (T4), a hormone produced by the thyroid gland. It is used to treat hypothyroidism, ensuring the body has sufficient thyroid hormone to regulate metabolism, energy levels, and overall health. Levothyroxine is converted into triiodothyronine (T3) in the body, which then influences the metabolism of cells. Adequate levels of thyroid hormones are needed for the maintenance of normal metabolic rates.
What are the potential interactions between phentermine and levothyroxine?
Phentermine is contraindicated in individuals with a history of cardiovascular disease, hyperthyroidism, glaucoma, and drug abuse. Also, it should be used with caution in patients with diabetes. So, what about hypothyroidism? Can a person take phentermine if they have hypothyroidism and are already taking levothyroxine?
The answer to this question is not so clear-cut, as a direct interaction between these two drugs has not yet been observed, according to the latest available research. Moreover, the FDA labels and prescribing information for both phentermine (LOMAIRA™) and levothyroxine (SYNTHROID™) do not list a direct contraindication for using these medications together. However, it is important to note that both medications can increase heart rate and blood pressure. When taken together, these effects could potentially be heightened, especially in patients with pre-existing heart conditions or patients whose hypothyroidism treatment might already impact their heart rate and metabolism. In fact, researchers believe that a levothyroxine overdose, particularly when paired with weight loss drugs like phentermine, can cause severe and potentially fatal health problems.
Studies have shown that hypothyroid patients often have altered drug metabolism. Fortunately, levothyroxine helps normalize metabolism. However, levothyroxine also has a narrow therapeutic index, meaning there is a small difference between the effective dose and the dose that causes side effects. In other words, it can be easy to take too little or too much, leading to health problems. For this reason, adding a stimulant like phentermine may result in unpredictable effects on metabolic rate (how quickly your body breaks down and uses a drug) and drug clearance (how fast your body removes a drug from your system). For instance, since levothyroxine should ideally be taken on an empty stomach for optimal absorption, phentermine may affect gastrointestinal motility and could theoretically interfere with the absorption of levothyroxine if not properly timed.
At the end of the day, this topic is not very well researched, and so the scarcity of evidence of a strong drug interaction between these two drugs makes it hard to conclude that there are indeed adverse interactions between levothyroxine and phentermine in all cases. The general consensus, therefore, seems to be that taking these two drugs at the same time can be safe, but can only be determined on a case-by-case basis. But, if you’re still concerned about having to take both at the same time, it’s best to share your concerns with your doctor and follow their guidance.
Tips for managing these two medications
Before you can take these medications together, you will have to discuss your full medical history and any potential risks with your healthcare provider. They may recommend an alternative weight loss drug if phentermine is likely to cause problems. If you experience new or worsening symptoms, such as chest pain, rapid heartbeat, dizziness, or unusual fatigue, contact your healthcare provider immediately.
Here are some best practices for taking phentermine
- Take phentermine exactly as prescribed by your doctor.
- Avoid taking it late in the day to prevent insomnia.
- Combine with a balanced diet and regular exercise.
- For optimal absorption, take levothyroxine on an empty stomach, either in the morning or evening, and maintain a consistent daily schedule.
- Avoid consuming foods or supplements that interfere with its absorption, such as calcium and iron, within four hours of taking the medication.
- Be sure to have your thyroid hormone levels monitored as regularly as recommended by your doctor.
- For more specific and detailed guidelines on how to take levothyroxine, kindly read the American Thyroid Association (ATA)’s Guidelines for the Treatment of Hypothyroidism published in 2014.
Key takeaways
- Phentermine is typically prescribed for people who are overweight or obese and have not been able to lose enough weight through diet and exercise alone.
- Levothyroxine is a synthetic thyroid hormone prescribed for the treatment of hypothyroidism. Levothyroxine is not meant to be used for weight loss.
- While it is possible to take phentermine and levothyroxine together, it should be done under strict medical supervision.
- Before your doctor prescribes phentermine for you while you’re already on medication, they will first make sure it is safe to take both based on your individual health status.
- Regular monitoring and open communication with your healthcare provider are essential to ensure safe and effective treatment.
- Always follow your doctor’s guidelines closely, and report any side effects or concerns promptly to ensure the best outcomes for your health.
