Phentermine

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Generic Name: Phentermine Brand Name(s): Generics only. No brands available.

Uses

What is phentermine used for?

Phentermine is used along with a doctor-approved, reduced-calorie diet, exercise, and behavior change program to help you lose weight. It is used in people who are significantly overweight (obese) and have not been able to lose enough weight with diet and exercise alone. Losing weight and keeping it off can reduce the many health risks that come with obesity, including heart disease, diabetes, high blood pressure, and a shorter life.

It is not known how this medication helps people to lose weight. It may work by decreasing your appetite, increasing the amount of energy used by your body, or by affecting certain parts of the brain. This medication is an appetite suppressant and belongs to a class of drugs called sympathomimetic amines.

How should I take phentermine?

Take this medication by mouth as directed by your doctor, usually once a day, 1 hour before breakfast or 1 to 2 hours after breakfast. If needed, your doctor may adjust your dose to take a small dose up to 3 times a day. Carefully follow your doctor’s instructions. Taking this medication late in the day may cause trouble sleeping (insomnia).

If you are using sustained-release capsules, the dose is usually taken once a day before breakfast or at least 10 to 14 hours before bedtime. Swallow the medication whole. Do not crush or chew sustained-release capsules. Doing so can release all of the drug at once, increasing the risk of side effects.

If you are using the tablets made to dissolve in the mouth, the dose is usually taken once a day in the morning, with or without food. First, dry your hands before handling the tablet. Place your dose on top of the tongue until it dissolves, then swallow it with or without water.

The dosage is based on your medical condition and response to therapy. Your doctor will adjust the dose to find the best dose for you. Use this medication regularly and exactly as prescribed in order to get the most benefit from it. To help you remember, take it at the same time(s) each day.

This medication is usually taken for only a few weeks at a time. It should not be taken with other appetite suppressants. The possibility of serious side effects increases with longer use of this medication and use of this drug along with certain other diet drugs.

This medication may cause withdrawal reactions, especially if it has been used regularly for a long time or in high doses. In such cases, withdrawal symptoms (such as depression, severe tiredness) may occur if you suddenly stop using this medication. To prevent withdrawal reactions, your doctor may reduce your dose gradually. Consult your doctor or pharmacist for more details, and report any withdrawal reactions immediately.

Rarely, abnormal drug-seeking behavior (addiction) is possible with this medication. Do not increase your dose, take it more frequently, or use it for a longer time than prescribed. Properly stop the medication when so directed.

This medication may stop working well after you have been taking it for a few weeks. Talk with your doctor if this medication stops working well. Do not increase the dose unless directed by your doctor. Your doctor may direct you to stop taking this medication.

How do I store phentermine?

Phentermine is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store phentermine in the bathroom or the freezer. There may be different brands of phentermine that may have different storage needs. It is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush phentermine down the toilet or pour them into a drain unless instructed to do so. It is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Precautions & warnings

What should I know before using phentermine?

Before using this drug, tell your doctor if:

  • You are pregnant or breastfeeding. This is because, while you are expecting or feeding a baby, you should only take medicines on the recommendation of a doctor.
  • You are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • You have allergy with any of active or inactive ingredients of phentermine or other medications.
  • You have any other illnesses, disorders, or medical conditions.

Do not use phentermine if you have taken an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, phenelzine, rasagiline, selegiline, and tranylcypromine.

You should not take phentermine if you have:

  • A history of heart disease (coronary artery disease, heart rhythm problems, congestive heart failure, stroke)
  • A history of pulmonary hypertension
  • Severe or uncontrolled high blood pressure
  • Overactive thyroid
  • Glaucoma
  • If you are in an agitated state
  • If you have a history of drug or alcohol abuse
  • If you are allergic to other diet pills, amphetamines, stimulants, or cold medications

Taking phentermine together with other diet medications such as fenfluramine (Phen-Fen) or dexfenfluramine (Redux) can cause a rare fatal lung disorder called pulmonary hypertension. Do not take this medicine with any other diet medications without your doctor’s advice.

Phentermine may be habit forming. Never share phentermine with another person, especially someone with a history of drug abuse or addiction. Keep the medication in a place where others cannot get to it.

Is it safe during pregnancy or breastfeeding?

There are no adequate studies in women for determining risk when using phentermine during pregnancy or while breastfeeding. Please always consult with your doctor to weigh the potential benefits and risks before taking phentermine. Phentermine is pregnancy risk category X, according to the US Food and Drug Administration (FDA).

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Side effects

What side effects can occur from phentermine?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

  • Feeling short of breath, even with mild exertion
  • Chest pain, feeling like you might pass out
  • Swelling in your ankles or feet
  • Pounding heartbeats or fluttering in your chest
  • Confusion or irritability, unusual thoughts or behavior
  • Feelings of extreme happiness or sadness
  • Dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, chest pain, shortness of breath, uneven heartbeats, seizure)

Less serious side effects may include:

  • Feeling restless or hyperactive
  • Headache, dizziness, tremors
  • Sleep problems (insomnia)
  • Dry mouth or an unpleasant taste in your mouth
  • Diarrhea or constipation, upset stomach
  • Increased or decreased interest in sex, impotence

Not everyone experiences these side effects. There may be some side effects not listed above. If you have any concerns about a side-effect, please consult your doctor or pharmacist.

Interactions

What drugs may interact with phentermine?

Phentermine may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. For your safety, do not start, stop, or change the dosage of any drugs without your doctor’s approval.

Products that may interact with this drug are:

  • Brofaromine
  • Clorgyline
  • Furazolidone
  • Iproniazid
  • Isocarboxazid
  • Lazabemide
  • Linezolid
  • Moclobemide
  • Nialamide
  • Pargyline
  • Phenelzine
  • Procarbazine
  • Rasagiline
  • Selegiline
  • Sibutramine
  • Toloxatone
  • Tranylcypromine

Does food or alcohol interact with phentermine?

Phentermine may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with phentermine?

Phentermine may interact with your health condition. This interaction may worsen your health condition or alter the way the drug works. It is important to always let your doctor and pharmacist know all the health conditions you currently have.

Health conditions that may interact with this drug are:

  • Agitated state (very nervous or anxious)
  • Arrhythmias (abnormal heart rhythms)
  • Arteriosclerosis (hardening of the arteries)
  • Congestive heart failure
  • Drug abuse or dependence
  • Glaucoma
  • Heart or blood vessel disease (e.g. coronary artery disease)
  • Hypertension (high blood pressure) that is not controlled
  • Hyperthyroidism (overactive thyroid)
  • Stroke
  • Heart valve disease
  • Hypertension (high blood pressure)
  • Pulmonary hypertension (elevated pressure in the lungs)
  • Kidney disease

Dosage

The information provided is not a substitute for any medical advice. You should ALWAYS consult with your doctor or pharmacist before using phentermine.

What is the dose of phentermine for an adult?

Usual Adult Dose for Weight Loss

The recommended dose is 15 to 37.5 mg orally once a day before breakfast or 1 to 2 hours after breakfast.

What is the dose of phentermine for a child?

Usual Pediatric Dose for Weight Loss

17 years or older:

The recommended dose is 15 to 37.5 mg orally once a day before breakfast or 1 to 2 hours after breakfast.

How is phentermine available?

Phentermine is available in the following dosage forms and strengths:

  • Tablets and Capsule, Oral, as hydrochloride: 37.5 mg; 15 mg; 30 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to your nearest emergency room.

What should I do if I miss a dose?

If you miss a dose of phentermine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose.

Hello Health Group does not provide medical advice, diagnosis or treatment.

msBahasa Malaysia

Review Date: July 18, 2017 | Last Modified: July 25, 2017

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