Also called phentermine

Duromine is used as a weight-loss treatment in people with a body mass index (BMI) of 30 or more. Find out how to take it safely and possible side effects.

Type of medicine Also called
  • Medicine for weight loss
  • Appetite suppresant
  • Duromine  

What is Duromine?

Duromine is used as a weight-loss treatment in people with a body mass index (BMI) of 30 or more who have not been able to lose weight with lifestyle changes. Read more about BMI.

Duromine suppresses appetite and can help weight loss by decreasing your hunger or making you feel full longer. Duromine is best used together with a healthy, balanced diet and regular exercise, as part of an overall weight-loss plan. 

In New Zealand, Duromine is available as capsules (15 mg and 30 mg) and only with a doctor's prescription. 


  • The usual dose of Duromine is 1 capsule (15 mg or 30mg) once a day in the morning.
  • Your doctor will tell you the best dose for you.
  • Increasing the dose may not necessarily make you lose more weight or lose weight faster. But if you have a higher dose, you will most likely experience more side effects.  
  • Always take your Duromine exactly as your doctor has told you.
  • The pharmacy label on your medicine will tell you how much to take, how often to take it and any special instructions.

How to take Duromine

  • Take Duromine first thing in the morning, at breakfast time so that it does not keep you awake at night.
  • It doesn't matter if you take this medicine before or after food.
  • If you forget to take your Duromine dose at breakfast take it no later than lunchtime. Or skip the dose you missed and take your next dose at the normal time on the next day.
  • If you take Duromine any later than lunchtime you may have trouble sleeping at night.
  • Never take a double dose to make up for a dose you have missed.  

Precautions – before taking Duromine

  • Do you have high blood pressure?
  • Do you have heart problems such as angina (chest pain)?
  • Do you have diabetes?
  • Do you have epilepsy? 
  • Do you have an overactive thyroid?
  • Do you have glaucoma?
  • Are you pregnant or breastfeeding?

If so, it’s important to tell your doctor or pharmacist before you start Duromine. Sometimes a medicine isn’t suitable for a person with certain conditions, or it can only be used with extra care.

Side effects

Like all medicines, Duromine can cause side effects, although not everyone gets them. Duromine is a stimulant that acts on the central nervous system. 

Common side effects of phentermine include:

  • increased heart rate
  • nausea and vomiting
  • dry mouth
  • sleeplessness
  • nervousness
  • diarrhoea (runny poos) and constipation.

This medicine may make you dizzy. If this happens do not drive or use tools or machines.

If you get breathlessness, chest pain, fainting or swelling in your legs, or you are not able to exercise as much as usual, see your doctor immediately.

Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product

Learn more

The following links have more information on Duromine:

Duromine Medsafe Consumer Information Sheet


  1. Phentermine NZ Formulary 
  2. Weight loss: the options and the evidence BPAC, NZ, 2019
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 09 Nov 2020