An image of a woman standing with a bathroom scale and a tape measure around her waist due to phentermine weight loss.

Phentermine for Weight Loss FAQs: Answering Your Top 21 Questions About This Weight Management Aid

Dr. Matthew Olesiak
SANE MD Chief Medical Director at SANESolution

Phentermine has become a promising option for a certain subset of individuals seeking to lose weight, especially when other methods have fallen short. It can help reduce body weight and is often prescribed based on body mass index (BMI) thresholds, such as a BMI of 30 kg/m2 or greater for obesity or a BMI of 27 kg/m2 or greater when other risk factors like high blood pressure or diabetes are present.

In this FAQ guide, we’ll dive into the most common questions surrounding this medication to help you understand its purpose and how it can be used effectively.

Key Takeaways:

  • Phentermine is a short-term prescription medication that helps curb appetite for certain individuals struggling with weight management.
  • It’s important to use phentermine under medical supervision, as side effects and potential risks should be carefully monitored.
  • Phentermine is not a long-term weight management solution, and its use should be paired with lifestyle changes for lasting results.

1. What is phentermine, and how does it help with weight loss?

Phentermine is a prescription medication used to help control appetite. It works by influencing the neurotransmitters in the brain, potentially making you feel less hungry. For those dealing with obesity, this can make sticking to a reduced-calorie diet easier.

Phentermine is often prescribed for a certain subset of individuals with a body mass index (BMI) of 30 kg/m2 or greater or 27 kg/m2 or greater when other risk factors like high blood pressure or diabetes are present. It has been shown to help reduce body weight by 5% to 10% when combined with a balanced diet and exercise. 

2. Is it safe to take phentermine?

Phentermine is considered safe for short-term use as long as you’re under the supervision of a healthcare provider. (Since it can lead to side effects like increased heart rate and dependency, it’s not intended for long-term use.) However, it can lead to side effects like increased blood pressure, which may manifest as severe headaches, blurred vision, and anxiety.

It’s crucial to consult a healthcare professional to monitor these potential adverse effects and ensure safe use.

3. How long can I be on phentermine?

Typically, phentermine is prescribed for up to 12 weeks. The medication is meant for short-term use, as prolonged exposure can reduce its effectiveness and heighten the risk of side effects.

Once your treatment ends, your doctor will discuss long-term strategies for maintaining your progress.

4. What side effects, such as increased blood pressure, might I experience while taking phentermine?

Some of the common side effects include dry mouth, insomnia, dizziness, and a rapid heartbeat. Chest pain is a serious side effect that requires immediate medical attention. Some individuals may also experience anxiety or feelings of restlessness. Decreased ability to exercise is another potential side effect. Symptoms such as exercise dizziness, fainting, or a fast heartbeat may arise during or after exercise and should be reported to a healthcare provider.

While these usually subside as your body adjusts, make sure to let your doctor know if any side effects persist or worsen.

5. Can I take phentermine with other medications?

Phentermine doesn’t mix well with certain medications, especially those that impact the central nervous system or stimulate appetite suppression. It is crucial to know your Weight Loss Drug Type (quiz here) and consult a healthcare professional before combining phentermine with other weight loss drugs to ensure safety and avoid potential health risks.

Make sure to let your doctor know about all the prescription and over-the-counter medications you are taking to prevent any harmful interactions.

5 Facts about Phentermine for Weight Loss Infographic

6. Is phentermine a controlled substance similar to amphetamines?

Phentermine shares some chemical similarities with amphetamines, and both work as stimulants. However, phentermine is not the same as amphetamines and has a lower risk for abuse when taken properly.

Despite this, it’s still classified as a controlled substance due to its potential for misuse.

7. Who should avoid taking phentermine?

Phentermine isn’t suitable for everyone. Those with heart problems, high blood pressure, uncontrolled high blood pressure, glaucoma, or a history of drug abuse should not take it.

Pregnant or breastfeeding women should also steer clear. Consult with your doctor to ensure phentermine is safe for you.

8. Is phentermine a long-term weight-loss solution?

No, phentermine is designed for short-term weight loss. It’s typically used to jumpstart weight loss, but your doctor may suggest other treatments or lifestyle changes for long-term management.

Achieving lasting weight loss involves making a sustained commitment to healthy habits rather than relying solely on medication.

9. What should I avoid while taking phentermine?

It’s best to avoid alcohol while on phentermine, as it can intensify side effects like dizziness or an increased heart rate.

Also, steer clear of other stimulants or appetite suppressants unless your doctor specifically says they’re safe to take together.

10. Can phentermine change my mood?

Phentermine can impact mood in some cases. Some people experience heightened anxiety or irritability, while others may feel restless or have trouble sleeping.

If you notice these changes affecting your daily life, consult your doctor for advice.

11. Do I need to follow a reduced-calorie diet while taking phentermine?

There’s no specific diet required while on phentermine, but for the medication to work effectively, it’s essential to follow a healthy, calorie-controlled meal plan. Phentermine may affect blood sugar levels, so patients with diabetes should consult their healthcare provider for potential dietary or medication adjustments.

Phentermine works best for compatible individuals when paired with balanced eating and regular exercise. Your healthcare provider or nutritionist can guide you toward a plan that fits your goals.

12. What should I do if I miss a dose of phentermine?

If you miss a dose, take it as soon as you remember. But if it’s close to your next scheduled dose, skip the missed one.

Never double up, as that can lead to side effects like jitters or a rapid heart rate.

13. How soon will I see results with phentermine?

Many people start noticing weight loss results within the first few weeks of using phentermine, especially when it’s combined with healthy eating and regular activity.

However, results vary depending on Weight Loss Drug Type, metabolism, dietary habits, and overall activity level.

14. Does phentermine cause withdrawal symptoms?

If phentermine is used long-term and then stopped suddenly, some people may experience withdrawal symptoms like fatigue, extreme hunger, or mood changes.

It’s best to follow your doctor’s advice about tapering off the medication to prevent these symptoms.

15. Is phentermine safe to take during pregnancy?

Phentermine is not recommended for use during pregnancy. It has not been studied in pregnant women and could pose risks to both the mother and baby.

If you become pregnant while on phentermine, contact your doctor immediately to discuss stopping the medication.

16. How does phentermine compare to other weight loss medications?

Phentermine is often compared to other weight loss drugs and weight loss medications for its potential effectiveness in reducing appetite.

Other medications, like orlistat or liraglutide, may be prescribed for longer-term use, and each has its own set of benefits and side effects.

Talk to your doctor about which option is best for you based on your health and goals.

17. What is a phentermine and topiramate combination?

Phentermine and topiramate, marketed under the brand name Qsymia, is a combination medication used for weight loss in adults with obesity. This duo combines phentermine, an appetite suppressant, with topiramate, an anticonvulsant that also promotes weight loss. Together, they have been shown to be promising in helping certain individuals shed pounds and improve weight-related health conditions.

When taking phentermine and topiramate, it’s crucial to follow your healthcare provider’s dosage instructions carefully. Typically, the starting dose is 3.75 mg of phentermine and 23 mg of topiramate, taken once daily in the morning. Your doctor may adjust the dose based on your response to the medication.

Common side effects of this combination include dry mouth, constipation, tingling sensations in the hands and feet, changes in taste, and fatigue. However, serious side effects can also occur, such as increased heart rate and blood pressure, suicidal thoughts or behaviors, seizures, and eye problems. Always discuss any concerns or questions with your healthcare provider before starting this medication.

18. What is the correct dosage and administration of Phentermine?

Phentermine comes in various forms, including tablets, capsules, and orally disintegrating tablets, each with specific administration guidelines.

  • Tablets and Capsules: Take phentermine once daily in the morning, with or without food. Swallow the tablet or capsule whole without crushing or chewing.
  • Orally Disintegrating Tablets: Place the tablet on your tongue and let it dissolve. Do not swallow the tablet whole.

The usual adult dose of phentermine is 8 mg taken orally three times a day, 30 minutes before meals, or 15-37.5 mg taken orally once a day, either before breakfast or 1-2 hours after breakfast. Avoid taking phentermine in the evening, as it can cause insomnia.

If you miss a dose, skip it and take your next dose at the usual time. Never take extra doses to make up for a missed dose.

19. How Long Does Phentermine Stay in Your System?

Phentermine is a controlled substance that can linger in your system for up to 4 days after the last does. 

The exact duration depends on factors such as the dose and frequency of use, individual metabolism, and kidney function, as well as the presence of other medications or substances.

20. Is Phentermine Affordable?

The cost of phentermine can vary based on the specific product, dosage, and location. On average, a 30-day supply of phentermine ranges from $30 to $100. Fortunately, there are several ways to save on this medication:

  • Use a coupon or discount card: Programs like GoodRx, Blink Health, SingleCare, and WellRx offer significant savings.
  • Buy a generic version: Generic phentermine is often more affordable than brand-name versions.
  • Purchase a larger quantity: Buying in bulk can reduce the overall cost.
  • Use a mail-order pharmacy: These services often provide lower prices and added convenience.

Comparing prices and exploring these options can help you find the best deal for your budget.

21. Are there Alternatives to Phentermine?

If phentermine isn’t the right fit for you, there are several other weight-loss medications to consider:

  • Orlistat (Alli, Xenical): This medication works by reducing fat absorption in the digestive tract.
  • Liraglutide (Saxenda): Liraglutide helps reduce hunger and increase feelings of fullness.
  • Bupropion-naltrexone (Contrave): This combination medication also helps to reduce hunger and enhance satiety. 
  • Qsymia (phentermine-topiramate): A combination of phentermine and topiramate that works by suppressing appetite and increasing feelings of fullness.

Knowing your Weight Loss Drug Type (quiz here) and discussing these options with your healthcare provider can help you determine the best choice for your individual needs and health status.

Conclusion

By providing answers to these common questions, we hope this guide has clarified how phentermine works and what you can expect. Always consult with your healthcare provider to ensure phentermine is the right choice for your weight loss journey.

References

https://www.phentermine.com/

https://www.drugs.com/phentermine.html#:~:text=Phentermine%20is%20used%20to