Phentermine - oral

Patient Medicine Information
Why do I need this medicine?
Phentermine is used to treat obesity.

This medicine is meant to be taken as part of a complete weight management programme that should include exercise, a healthy diet and other lifestyle changes.
How do I take this medicine?
Take Phentermine exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.

Take this medicine before breakfast. It is best to take Phentermine early in the day to avoid difficulty sleeping at night. Do not take Phentermine at bedtime.

Phentermine is available as a capsule, tablet or as an orally disintegrating tablet.

If you are taking capsules or tablets, swallow it whole. Do not divide, chew or crush the medicine.

If you have been given the orally disintegrating tablet:
  1. Remove it from the foil only just before you take it. Do not leave the orally disintegrating tablet exposed to air. Do not push the tablet through the foil as it is fragile and can break easily.
  2. Remove the tablet with dry hands by peeling the backing off the foil and tipping the tablet onto your dry hands.
  3. Place the orally disintegrating tablet directly on your tongue as soon as it is taken out of the foil. The tablet will immediately start to melt on the tongue. It can then be swallowed with or without water.
What should I do if I have forgotten to take this medicine?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.

DO NOT double a dose under any circumstances.

If you often forget to take your medicine, let your doctor and pharmacist know.
When should I not use this medicine?
Alert your doctor if you have the following conditions:
  • heart failure (weakness and inability of the heart to pump blood)
  • heart valve abnormality
  • stroke
  • high blood pressure
  • arrhythmia (irregular or abnormal heartbeat)
  • coronary artery disease (disorder of the blood vessels of the heart)
  • thyroid disease
  • atherosclerosis (hardening and thickening of the artery)
  • depression or other mental illness
  • history of drug abuse
  • agitated state
  • glaucoma (increased pressure in the eye)

Do not take Phentermine if you are pregnant or planning to have a baby soon. If you become pregnant while being treated with this medicine, alert your doctor immediately. Phentermine may cause harm to your unborn child. You must use proven birth control methods while taking this medicine.

Do not breastfeed while you are being treated with this medicine.

Do not take Phentermine if you are taking or have taken medicines to treat depression known as MAOI (monoamine oxidase inhibitor) such as isocarboxacid, phenelzine and tranylcypromine in the last 14 days.
What should I take note of while taking this medicine?
Inform your doctor if you have the following conditions:
  • kidney disease
  • epilepsy (fits or seizures)
  • diabetes
  • Tourette's syndrome also known as tics (a condition characterised by uncontrolled speech or body movements)

What lifestyle changes should I make to lose weight and maintain my ideal weight?

A healthy, balanced diet and regular exercise are keys to helping you maintain your ideal weight. You should avoid relying only on medication to maintain your ideal weight. Try to control the type and amount of food you eat at each meal. If you have not been exercising, start slow and gradually step up your exercise capacity. You will find that keeping to a regular exercise regimen is enjoyable and helps keep your weight off. If stress causes you to reach out for snacks too often, replace unhealthy snacks with healthier choices and learn to manage your stress levels. Alcohol also commonly causes weight gain. Try to avoid alcohol or set a limit on how much you drink.

Do not share this medicine with anyone else, even if they are overweight. Phentermine may not be suitable for everyone.
What side effects could I experience?
Phentermine may cause dizziness. If affected, do not drive or take part in any activity in which you need to be alert.

Other side effects include any of the following: palpitation, headache, dry mouth, unpleasant taste in the mouth, problems sleeping, nausea, constipation, diarrhoea, nervousness, libido changes and tiredness.

Some side effects may need immediate medical help. Alert your doctor quickly if you experience any of the following:
  • shortness of breath
  • chest pain
  • loss of consciousness

Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Can I take this with other medicines?
Do not take Phentermine with medicines to treat depression known as MAOI (monoamine oxidase inhibitor) such as isocarboxazid, phenelzine and tranylcypromine in the last 14 days.

Inform your doctor and pharmacist if you are taking medicines for heart disease e.g. clonidine, methyldopa and guanethidine.

Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.
What special dietary instructions should I follow?
Avoid alcohol.

It is important for you to maintain a healthy, low-fat and balanced diet.
How should I store this medicine?
Store in a cool, dry place away from the reach of children.

Medicines must not be used past the expiry date.
This information is independently developed by MIMS based on phentermine - oral and is provided for your reference only. It is not a replacement for and should only be used in conjunction with full consultation with a licensed healthcare professional, the information provided by your pharmacist and/or the manufacturer of the medication. It may not contain all the available information you require and cannot substitute professional medical care, nor does it take into account all individual circumstances. Although great effort has been made to ensure content accuracy, we shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2023 MIMS. All rights reserved. Powered by
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