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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.


Drug Starting dose Available doses Weight loss vs placebo (% or kg) Side Effects Contraindications
Phentermine 15 mg 15, 30, 40 mg 3.6-4.5 kg in 6 months Insomnia, dry mouth, agitation, tachicardia Hypertension, glaucoma, history drug/alcohol abuse, SSRI antidepressants, pregnancy, heart disease
Orlistat 120 mg TDS 120 mg 2.9-3.4% in 1 year Steatorrhea, oil spotting, flatulence, incontinence, vitamin malabsorption pregnancy
Liraglutide 0.6 mg 0.6 – 3 5.4% in 1 year Nausea, Rare pancreatitis, cholecystitis Renal/hepatic insufficiency, pregnancy, psychiatric disorder, past pancreatitis
Naltrexone/Bupropion 8/90 mg 4.8% in 1 year Nausea, headache, dizzy and dry mouth Antidepressants,
Topiramate 12.5 mg mane 25, 50, 100 mg 3.4-5 kg Insomnia, dry mouth, paraesthesia, altered taste, dizziness, depression Glaucoma, renal stones, pregnancy Off label
Phentermine/topiramate 15 mg/12.5 mg mane 15/12.5- 100 mg 5-6.6% in 1 year As above As above Off label
Metformin 500 mg 500-2000 mg 0.6-1.2 kg Bloating, diarrhea, Vit B12 deficiency, hypoglycemia Renal problems Off label
SGLT-2 (dapagliflozin, canagliflozin, empagliflozin) 1.8 – 2.7 kg Genital and urinary tract infections Renal problems Off label