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Pharmacotherapy for obesity


Obesity is a serious, chronic, relapsing disease of energy regulation, with strong genetic and early-life environmental determinants.

Medications can be useful adjunct to lifestyle intervention in effecting and maintaining clinically significant weight loss in those with BMI >30, or 27-30 and obesity-related complications.

*Check BMI here.

Safety and efficacy should be monitored closely on commencement and the medication should be discontinued if there are safety or tolerability issues, or if <5% weight loss is observed after 3-4 months

For the majority of patients, following the exemplary diet and exercise recommendation provide only modest or no weight loss and difficulty to sustain.


DrugStarting doseAvailable dosesWeight loss vs placebo (% or kg)Side EffectsContraindications
Phentermine15 mg15, 30, 40 mg3.6-4.5 kg in 6 monthsInsomnia, dry mouth, agitation, tachicardiaHypertension, glaucoma, history drug/alcohol abuse, SSRI antidepressants, pregnancy, heart disease
Orlistat120 mg TDS120 mg2.9-3.4% in 1 yearSteatorrhea, oil spotting, flatulence, incontinence, vitamin malabsorptionpregnancy
Liraglutide0.6 mg0.6 – 35.4% in 1 yearNausea, Rare pancreatitis, cholecystitisRenal/hepatic insufficiency, pregnancy, psychiatric disorder, past pancreatitis
Naltrexone/Bupropion8/90 mg4.8% in 1 yearNausea, headache, dizzy and dry mouthAntidepressants,
Topiramate12.5 mg mane25, 50, 100 mg3.4-5 kgInsomnia, dry mouth, paraesthesia, altered taste, dizziness, depressionGlaucoma, renal stones, pregnancyOff label
Phentermine/topiramate15 mg/12.5 mg mane15/12.5- 100 mg5-6.6% in 1 yearAs aboveAs aboveOff label
Metformin500 mg500-2000 mg0.6-1.2 kgBloating, diarrhea, Vit B12 deficiency, hypoglycemiaRenal problemsOff label
SGLT-2 (dapagliflozin, canagliflozin, empagliflozin)1.8 – 2.7 kgGenital and urinary tract infectionsRenal problemsOff label