Key points about duromine

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

  • 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.
  • Don't take a double dose to make up for a dose you have missed.  

If you have any of the following, please discuss your options with your healthcare provider before taking Duromine as it may not be suitable for you:

  • high blood pressure
  • heart problems such as angina (chest pain)
  • diabetes
  • epilepsy 
  • an overactive thyroid
  • glaucoma
  • pregnant or breastfeeding.

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(external link)

The following links have more information on Duromine:

Duromine(external link) Medsafe Consumer Information Sheet



BMI calculator


  1. Phentermine(external link) NZ Formulary 
  2. Weight loss: the options and the evidence(external link) BPAC, NZ, 2019

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

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