- PhentermineLearn more about phentermine and how to get the most from your weight loss journey.
- ResourcesAdditional information and tools to help you make the most of your effort.
- AlternativesLearn more about the most popular weight loss medications and science-backed supplements
Frequently Asked Questions
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To receive a prescription for phentermine, you’ll need to follow these steps:
- Find a weight loss clinic (preferably near you) and call them to inquire about whether they prescribe phentermine. If yes, proceed to step 2.
- Schedule an in-person, face-to-face consultation with the clinic.
- During the consultation, you’ll receive a medical exam, have your BMI calculated, as well as answer questions for medical intake.
- The physician at the clinic will consider your stats and exam results, and make a decision about whether you qualify.
- If you qualify, the physician may write a prescription for phentermine, which you’d get filled at your local pharmacy.
For a detailed comparison of popular alternatives to phentermine, see our Phentermine Alternatives comparison chart.
These alternatives are available over the counter (OTC), meaning you don’t need a prescription to buy them. Most are available to purchase online.
Phentermine is not recommended for those people who are under the age of 16, not even carefully monitored dosages. Phentermine is usually not recommended for geriatric patients. One reason is that many elderly patients are not able to participate in an increased physical activity, making it difficult to begin an ongoing regimen for future progress. Also, many elderly require a variety of prescription medicines which may interact adversely with Phentermine.
Do not take Phentermine without a doctor’s approval if you:
- have a history heart disease
- have uncontrolled hypertension
- have glaucoma
- have an overactive thyroid
- are taking a Monoamine Oxidase Inhibitor (MAOI) now or in the past 14 days
- are pregnant or planning to become pregnant—could be dangerous to developing a fetus
- are breastfeeding
- are prone to agitation, extreme restlessness or irritability
- have a history of drug abuse
- suffer from kidney disease—could hasten the deterioration of kidney function
Discuss possible insulin fluctuations if you are diabetic. Always discuss any possible interactions with other regularly prescribed medications. Also, do not drive a car or heavy equipment until you know how taking Phentermine will affect you.(2)
Phentermine works in the nervous system by stimulating the release of certain chemicals that may make you feel like your stomach is full. As a result, you will eat less. Along with curbing appetite, the drug reduces the body’s ability to absorb starch and fat, allowing them to pass through the body without being metabolized. This result in quicker weight loss than diet alone. (2)
Although some weight loss may be achieved by Phentermine alone, the best results will be achieved when combined with counseling to change harmful habits and address underlying issues associated with severe weight gain. It is recommended that this weight-loss supplement is taken for limited periods of time to avoid any possibility of addiction or serious side effects.
Phentermine may affect how other medications work in your body or vice versa. Also, combining this medication with others may also increase or worsen potential side effects. Avoid taking any other OTC weight-loss drugs while taking Phentermine.
Consult your doctor before taking Phentermine if you are taking:
- MAOIs for depression
- Adrenergic neuron blocking drugs to control high blood pressure or psychotic symptoms
- Selective serotonin reuptake inhibitors (SSRIs) for the treatment of depression or anxiety
The most common side effects of Phentermine are:
- Dry mouth
- Difficulty sleeping—usually occurs in the first week and then goes away
- Increased heart rate/blood pressure
- Stomach upset such as either constipation or diarrhea
- Itchy skin (2)
If you experience itching which worsens or a severe rash appears, discontinue use and consult your doctor. Also, if you have ongoing problems with insomnia you should seek professional counsel about dosage adjustments or alternatives.
More serious side effects sometimes occur. Most can be avoided by a limited regimen and strict dosage control of the weight-loss medication. Ongoing studies indicate that these side effects are rare with short-term usage.
If anyone who suffers from cardiac problem should regularly monitor the effects for any potential complications.(3) Some of the more serious side effects could include:
- Primary Pulmonary Hypertension—a rare but fatal disease of the lungs. Stop taking Phentermine and seek medical attention if you have difficulty breathing, severe chest pain, feel faint or nauseated, or experience swelling in the legs and feet.
- Heart valve disease