Phentermine is a stimulant drug that is commonly used for weight loss. It works by decreasing appetite and increasing the feeling of fullness. The FDA has approved the weight loss medicine phentermine for use in conjunction with behavioral modification, calorie restriction, and physical activity.
People with a body mass index (BMI) of 30 kg/m2 or more may be eligible for short-term phentermine medication. Individuals with a body mass index (BMI) of 27 kg/m2 or higher and additional risk factors, such as hypertension, diabetes, or elevated cholesterol, may also be prescribed this medication.
But will the drug starts working immediately, or will it have a buildup period inside your system? I will explain the half-life, use, efficacy, and potential; side effects of Phentermine as a weight loss drug.
Are Weight Loss Drugs Effective?
Drugs intended to help people lose weight are not successful for everyone. Generally, weight loss of 1-2 pounds each week is considered safe. When combined with a healthy diet and regular physical activity, most weight loss medications cause a 5-10% reduction in body weight within a year.
To put this in perspective, a patient weighing 200 pounds would lose 10–20 pounds over a year, which is well within the safe range for weight loss. Although this may not seem like much weight to lose, it could be enough to aid with blood pressure and have a beneficial influence on blood sugar.
Common weight loss drugs include:
- Ozempic, Wegovy (semaglutide)
- Contrave (bupropion and naltrexone)
- Qsymia (phentermine and topiramate)
- Saxenda (liraglutide)
How Long Does Phentermine Stay In Your System?
On average, phentermine has a half-life of about 19-24 hours, meaning it takes this long for the drug to be metabolized and eliminated from your body. However, the drug can be detected in your system for longer periods, particularly if you take high doses or have been taking it for an extended time.
Phentermine can generally be detected in urine for up to 3-4 days after the last dose. It can also be detected in blood for up to 48 hours after the last dose. In some cases, the drug may be detectable in hair for up to 90 days after the last dose.
Does Phentermine Build Up In Your System?
It takes 3 to 5 days for Phentermine to build up in your system, and the time is called a steady state. Within this period, you may not feel the drug’s full potential.
The steady state may vary depending on the user’s overall physical condition, metabolism rate, and age. If you have an active lifestyle and rely more on a balanced diet, the time can be less than three days.
How Does Phentermine Work?
Phentermine is a stimulant drug that is commonly used for weight loss. It works by decreasing appetite and increasing the feeling of fullness. It does this by stimulating the release of chemicals in the brain, such as norepinephrine and dopamine, which help to reduce hunger and cravings.
When taken as directed, phentermine can help suppress appetite and make it easier to stick to a calorie-restricted diet, leading to weight loss if you are in a calorie deficit.
Phentermine Dosage
Phentermine is typically taken orally as a capsule or tablet and is usually taken once a day before breakfast or 1-2 hours after breakfast. Notably, phentermine is not a magic solution for weight loss and should be used with a balanced diet and regular physical activity.
In addition, phentermine is a controlled substance and is only available by prescription. It is not recommended to take this drug without the supervision of a healthcare provider. If you are interested in using phentermine for weight loss, discuss it with your healthcare provider to determine if it is the right option.
Is Semaglutide Better Than Phentermine For Weight Loss?
The GLP-1 receptor agonist semaglutide is the most effective treatment for weight loss compared to Phentermine and other weight loss drugs. However, semaglutide’s side effects are also more adverse than the other medications.
Semaglutide is typically recommended for people who are obese or have a significant amount of weight to lose and have been unable to achieve substantial weight loss through diet and exercise alone. Phentermine is also used for weight loss, but it is typically only recommended for short-term use and may not be suitable for everyone.
Does Phentermine Burn Fat or Just Suppress Appetite?
While phentermine can help to suppress appetite and make it easier to stick to a calorie-restricted diet, it is not explicitly designed to “burn fat.” Instead, it works by helping you to consume fewer calories overall, which can lead to weight loss if you are in a calorie deficit.
Following a balanced diet and regular physical activity are essential for weight loss. Phentermine can be a useful tool for weight loss combined with these lifestyle changes, but it is not a magic solution.
It is important to discuss your weight loss goals and treatment plan with your healthcare provider to determine the best approach for you.
What Happens When You Stop Taking Phentermine?
When you stop taking phentermine, it is common to experience a range of withdrawal symptoms. These symptoms can vary in intensity and duration but may include the following:
- Increased appetite
- Cravings for food
- Fatigue
- Depression
- Insomnia
It is important to note that these symptoms are typically more severe in people taking high doses of phentermine for an extended period. These temporary symptoms will resolve independently within a few days to a week.
Phentermine Side Effects
Like all medications, phentermine can cause side effects. Common side effects of phentermine may include:
- Dry mouth
- Constipation
- Nausea
- Vomiting
- Diarrhea
- Stomach pain
- Dizziness
- Insomnia
Less common side effects of phentermine may include:
- Rapid heartbeat
- Chest pain
- High blood pressure
- Agitation
- Depression
- Tremor
- Decreased libido
It is important to note that this is not a complete list of all possible side effects of phentermine. If you take phentermine and experience any side effects, you should discuss them with your healthcare provider.
Final Words
The length of time that phentermine stays in your system can vary depending on several factors, including your age, weight, metabolism, and the specific formulation of the drug you are taking.
On average, phentermine has a half-life of about 19-24 hours, meaning it takes about this long for the drug to be metabolized and eliminated from your body. However, the drug can be detected in your system for longer periods, particularly if you take high doses or have been taking it for an extended time.
It is crucial to choose a weight loss medication appropriate for your circumstances and get professional help from Dr. David Nazarian.
