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) and liraglutide (Saxenda).

Three weight loss medicines are available in New Zealand but none of them are subsidised. You need to pay for the cost of the medicine in full.

Xenical (also called orlistat)

Xenical prevents the absorption of some of the fat you eat. 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 will increase the side effects of this medicine. Your daily intake of fat, carbohydrates and protein should be distributed 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, 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 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 or diarrhoea (runny poos)
  • 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 for women who 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 (BMI ≥27) who also have weight-related medical problems, or for people with a BMI ≥30 (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 poos), constipation, indigestion, wind and bloating. 


  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
Credits: Sandra Ponen, Pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 11 Nov 2020