Phentermine (often sold under brand names like Adipex-P or Lomaira) is a prescription-only stimulant medication used to assist with weight loss.It is chemically similar to amphetamines and works primarily as an appetite suppressant to help individuals with significant health risks related to obesity manage their weight.How It WorksPhentermine acts on the central nervous system to stimulate the release of neurotransmitters (specifically norepinephrine, and to a lesser extent, dopamine and serotonin). This reaction triggers a “fight-or-flight” response in the body, which:Significantly decreases your appetite and cravings.Helps you feel full faster and for longer periods.Primary Medical UsesBecause it is a powerful stimulant, Phentermine is prescribed strictly as a short-term aid (typically 12 weeks or fewer) for weight reduction. It is indicated for:Adults with a Body Mass Index (BMI) of $30\text{ kg/m}^2$ or greater (obese).Adults with a BMI of $27\text{ kg/m}^2$ or greater (overweight) who also have at least one weight-related medical condition, such as controlled high blood pressure, type 2 diabetes, or high cholesterol.It is always meant to be used alongside a doctor-approved plan of low-calorie diet, behavior modification, and regular physical exercise.Key Risks & Regulatory StatusDue to its chemical structure and potential side effects, Phentermine is classified as a Schedule IV controlled substance in the United States and is highly regulated or restricted in many countries.Abuse and Dependence: It carries a risk of habit-formation, physical dependence, and abuse.Cardiovascular Effects: Because it is a stimulant, it can cause a rapid heart rate (tachycardia), palpitations, and elevated blood pressure. It is generally avoided in patients with a history of heart disease, stroke, or severe high blood pressure.Common Side Effects: Other common side effects include insomnia (difficulty sleeping), restlessness, dry mouth, anxiety, and constipation.