Phentermine is a prescription medication for short-term weight management. It functions as an appetite suppressant, helping individuals reduce calorie intake and lose weight. It is used as part of a weight management program that includes exercise, behavioral changes, and a reduced-calorie diet.
Healthcare Professionals Who Prescribe Phentermine
Licensed healthcare professionals can prescribe phentermine, though regulations vary by state and scope of practice. Medical doctors (MDs) and osteopathic doctors (DOs) prescribe this medication, often in weight loss clinics or private practices, after a comprehensive evaluation.
Nurse practitioners (NPs) and physician assistants (PAs) also have prescriptive authority in many jurisdictions. Their ability to prescribe is governed by state laws and may require physician supervision or collaboration, depending on the state. Telehealth platforms also allow licensed providers to prescribe phentermine after a detailed health assessment.
Medical Criteria for Phentermine Prescription
Phentermine is prescribed based on specific medical criteria, primarily Body Mass Index (BMI). Patients typically qualify with a BMI of 30 kg/m² or greater (obesity). It may also be considered for individuals with a BMI of 27 kg/m² or greater who have at least one weight-related comorbidity.
These associated health conditions can include hypertension (high blood pressure), type 2 diabetes mellitus, or dyslipidemia (abnormal lipid levels). The medication aids weight loss by decreasing hunger or promoting fullness. It is used with a reduced-calorie diet and increased physical activity, and is reserved for those who have not achieved sufficient weight loss through diet and exercise alone.
The Prescription and Monitoring Process
Obtaining a phentermine prescription begins with an initial consultation. This involves a comprehensive review of medical history, a physical examination, and potential laboratory tests. The provider evaluates if phentermine is appropriate, considering existing medical conditions or other medications.
Once prescribed, the dosage is individualized for the lowest effective dose, usually 15 mg to 37.5 mg orally once daily in the morning. Regular follow-up appointments monitor progress, assess effectiveness, and check for side effects. This allows dosage adjustments or consideration of alternative treatments.
Phentermine is approved for short-term use, typically for a few weeks, up to 12 weeks. While some practitioners may use it longer, its long-term safety and efficacy are less established. Monitoring blood pressure and heart rate is important, especially for patients with controlled hypertension. If less than 5% weight loss is not achieved after 12 weeks, discontinuation or an alternative treatment may be considered.
Important Patient Considerations
Phentermine is classified as a Schedule IV controlled substance by the Drug Enforcement Administration (DEA), meaning it has a potential for abuse, though this appears low. This classification impacts prescribing and refilling; some states limit prescriptions to one month. Patients should not exceed the prescribed dose, frequency, or duration, as it can be habit-forming.
Common side effects include dry mouth, insomnia, constipation, headache, and increased heart rate. Rare but serious side effects, such as primary pulmonary hypertension and heart valve problems, have been reported, with risk increasing with longer use. Patients should immediately contact their doctor if they experience difficulty breathing, severe chest pain, fainting, or leg swelling.
Phentermine is contraindicated in several medical conditions, including cardiovascular disease (e.g., coronary artery disease, stroke, arrhythmias, uncontrolled hypertension, congestive heart failure), hyperthyroidism, glaucoma, agitated states, and a history of drug abuse. It should not be used during pregnancy, breastfeeding, or within 14 days of taking monoamine oxidase inhibitors (MAOIs) due to dangerous drug interactions. While phentermine can be an effective tool, sustained weight management requires ongoing commitment to lifestyle changes, including diet and exercise.