Phentermine Prescription: What You Need to Know Before Starting

Thinking about using phentermine for weight loss? You’re not alone—lots of people look for a quick boost to drop those stubborn pounds. But before you pop a pill, you should understand how a prescription works, the right dose, and the risks involved. This guide breaks down the basics in plain language so you can make an informed choice.

How to Get a Phentermine Prescription

Phentermine is a controlled substance, so you can’t just buy it over the counter. First, talk to a doctor—either in person or via a telehealth service that can prescribe weight‑loss meds. The doctor will ask about your medical history, current meds, and why you want to lose weight. If you have high blood pressure, heart disease, or are pregnant, phentermine isn’t a good fit.

Most doctors require that you’ve tried diet and exercise first. They may ask you to keep a food diary for a couple of weeks to see if lifestyle changes work before they write the script. If they decide phentermine is appropriate, they’ll give you a short‑term prescription—usually a few weeks to a few months.

Typical Dosage and How to Take It

Phentermine comes in tablets of 15 mg, 30 mg, or 37.5 mg. The usual starting dose is 15 mg once a day, taken early in the morning before breakfast. Some people need the 30 mg dose, but most doctors keep the dose low to avoid side effects.

Take the pill with a full glass of water and avoid food high in fat right after, as it can slow absorption. Don’t take it late in the day; the stimulant effect can keep you up at night. If you miss a dose, just skip it—don’t double up.

Common Side Effects and When to Call the Doctor

Because phentermine is a stimulant, you might feel a rush of energy, a faster heartbeat, dry mouth, or trouble sleeping. Most side effects are mild and fade after a week or two. If you notice dizziness, chest pain, severe anxiety, or mood swings, stop the medication and call your doctor right away.

Long‑term use can lead to tolerance—your body gets used to the drug and it stops working. That’s why doctors limit the treatment period and may suggest a break after a few months.

Tips for Staying Safe While Using Phentermine

Combine the medication with a balanced diet and regular exercise. Phentermine isn’t a magic bullet; it only works when you create a calorie deficit. Keep a log of what you eat and track your activity so you can see real progress.

Avoid alcohol and other stimulants like caffeine because they can raise blood pressure and cause jittery feelings. Stay hydrated—drink plenty of water throughout the day to combat dry mouth.

If you’re planning to stop phentermine, taper off slowly under your doctor’s guidance. Suddenly quitting can cause a rebound increase in appetite and mood changes.

Remember, the best weight‑loss plan is one you can keep for life. Phentermine can give you a short‑term push, but lasting results come from healthier habits built over time.