Weight loss medicines

Weight loss medicines are best used as part of an overall weight-loss plan that includes a healthy, balanced diet and regular exercise. Weight loss medicines available in New Zealand are orlistat (Xenical), phentermine (Duromine), liraglutide (Saxenda) and Contrave.

If you are overweight or obese, weight loss can improve your health and help prevent and treat acute (short term) and chronic (long term) medical conditions. 

Considerations when using weight loss medicines

Healthy, low calorie eating and regular exercise are the basics of weight loss that lasts. But for some people this is not enough and weight loss medicines may help. Weight loss medicines are not a ‘quick fix’, but a long-term option for managing obesity. They must be used in addition to, and not instead of, diet and exercise. In people who are overweight or obese, a sustained weight loss of 5% to 10% can have important health benefits, such as lowering blood pressure, blood sugar and triglyceride levels. When weight loss medicines are stopped, most people will regain weight over time. However, adopting healthy lifestyle habits may help limit weight gain.

Which weight loss medicines are available in Aotearoa New Zealand?

The weight loss medicines available in Aotearoa New Zealand are not subsidised. You need to pay for the cost of the medicine in full. The 4 weight loss medicines available are:

Xenical (also called orlistat)

Xenical is available as a capsule and is recommended for people with a BMI of 30 or more (obese). It prevents some of the fat you eat from being absorbed by your body. You should take it with liquids during a main meal or up to 1 hour after eating. If you miss a meal or eat a meal that contains no fat, you should skip your dose of Xenical.

Eat a well-balanced diet, high in fruit and vegetables, with less than 30% of calories from fat. More fat in your diet increases the side effects of this medicine. Your daily intake of fat, carbohydrates and protein should be spread out over 3 main meals.

Because Xenical may decrease the amount of some vitamins that your body absorbs from food, you may need to also take a multivitamin supplement once a day. Take the vitamin supplement at least 2 hours before or after taking Xenical. You may also take your multivitamin supplement at bedtime. 

Common side effects of Xenical are fatty or oily stools (poo), wind, stomach cramps and bloating. These usually occur if your diet is too high in fat. Read more about Xenical.

Duromine (also called phentermine)

Duromine is available as a capsule and is recommended for people with a BMI of 30 or more (obese). It is a stimulant that acts on your central nervous system. It is used to suppress your appetite. It can help weight loss by decreasing your hunger or making you feel full longer. 

Common side effects include:

  • increased heart rate
  • dry mouth
  • sleeplessness (staying awake)
  • nervousness
  • constipation (hard poo) or diarrhoea (runny poo)
  • nausea (feeling sick).

Duromine should not be used if you have heart disease, high blood pressure, an overactive thyroid gland or glaucoma. It also isn't suitable if you are pregnant, may become pregnant or are breastfeeding. Read more about Duromine.

Saxenda (also called liraglutide)

Saxenda suppresses your appetite by increasing feelings of fullness and reducing feelings of hunger, which can lead to eating fewer calories and losing weight. It is recommended for adults with excess weight (a BMI of 27 or more) who also have weight-related medical problems, or for people with a BMI of 30 or more (obese). 

Saxenda comes as an injection that it is given under the skin in your tummy area, upper arm or thigh. It is available on prescription only. Common side effects include feeling sick (nausea), diarrhoea (runny poo), constipation (hard poo), indigestion, wind and bloating. Read more about Saxenda.


Contrave contains 2 medicines in each tablet – naltrexone and bupropion. Contrave works on areas in your brain involved in the control of food intake and energy use.

It is recommended for adults with excess weight (a BMI of 27 or more) who also have weight-related medical problems, or for people with a BMI of 30 or more (obese). Contrave is not suitable in people who have (or have had) seizures, bipolar disorder and uncontrolled hypertension (high blood pressure). Common side effects include feeling sick (nausea), being sick (vomiting), dry mouth and constipation (hard poo).   


  1. Obesity and weight-loss management Research Review, NZ, 2020
  2. Weight loss – the options and the evidence BPAC, NZ, 2019
  3. Clinical guidelines for weight management of New Zealand adults Ministry of Health, NZ, 2017
  4. Contrave Medsafe, NZ
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 08 Dec 2020