Drug info

GLP-1 medicines

Diabetes and weight medicine Prescription only

Injections (and now tablets) that copy gut hormones controlling blood sugar and appetite. Same family, very different strengths. Social media calls them miracle drugs; the trials call them very effective, with fine print.

At a glance

For
Type 2 diabetes; weight management; some also lower heart attack and stroke risk or treat sleep apnoea
Works
Weight: from about 8% of body weight (liraglutide) to about 15% (semaglutide) and 15–21% (tirzepatide) over 1 to 1.5 years, versus 2–3% on a dummy treatment. Diabetes: HbA1c (3-month sugar average) down by roughly 1 to 2 points
Cost
PBS for type 2 diabetes only: Ozempic and Trulicity (criteria apply). None are on the PBS for weight loss, and Mounjaro isn’t on the PBS for anything (October 2026)
Kicks in
Appetite drops in the first weeks; doses stepped up about every 4 weeks; full effect over 1 to 1.5 years
Taken for
Long term: weight usually returns after stopping
Watch for
Nausea, vomiting, diarrhoea or constipation, reflux, gallstones

Not a miracle and not cheating: it’s a hormone. It turns down the food noise. Protein, sleep and moving are still your job.

Brand names

How it works

GLP-1 is a hormone your gut releases after eating. These medicines copy it and last much longer: they boost insulin when blood sugar is high, slow stomach emptying and tell the brain you’re full. Tirzepatide also copies a second gut hormone, GIP.

Used for

Compared

Same idea, different strength and dosing. Weight figures are average loss in the main trial, on the medicine versus a dummy treatment, with diet and activity advice in both groups.

  1. GLP-1Semaglutide (Ozempic, Wegovy, Rybelsus)
    How taken
    Weekly injection, or a daily tablet on an empty stomach (Rybelsus)
    Approved for
    Type 2 diabetes; weight; lowering heart risk; fatty liver with scarring (provisional)
    Weight loss
    STEP 1 (Wegovy 2.4 mg): 14.9% vs 2.4% over 68 weeks
    Blood sugar
    HbA1c down 1.5–1.8 points over 40 weeks (SUSTAIN 7)
    PBS
    Ozempic for type 2 diabetes only
    Notable
    SELECT trial: about 20% fewer heart attacks, strokes or heart deaths in people with heart disease and excess weight
  2. GIP and GLP-1Tirzepatide (Mounjaro)
    How taken
    Weekly injection
    Approved for
    Type 2 diabetes; weight; sleep apnoea with obesity
    Weight loss
    SURMOUNT-1: 15.0–20.9% (by dose) vs 3.1% over 72 weeks
    Blood sugar
    HbA1c down by about 2 points
    PBS
    No, for any use
    Notable
    Beat semaglutide head-to-head for weight: 20.2% vs 13.7% over 72 weeks (SURMOUNT-5). Can make the contraceptive pill less reliable
  3. GLP-1Liraglutide (Victoza, generics)
    How taken
    Daily injection
    Approved for
    Type 2 diabetes (Victoza); weight (3 mg generics)
    Weight loss
    SCALE: 8.0% vs 2.6% over 56 weeks. In a head-to-head trial (STEP 8), weekly semaglutide caused more than twice as much weight loss
    Blood sugar
    Lowers HbA1c
    PBS
    No
    Notable
    The older daily option; generic versions approved in 2025
  4. GLP-1Dulaglutide (Trulicity)
    How taken
    Weekly injection
    Approved for
    Type 2 diabetes only
    Weight loss
    Not approved for weight. 2.3–3.0 kg over 40 weeks in diabetes (SUSTAIN 7)
    Blood sugar
    HbA1c down 1.1–1.4 points (SUSTAIN 7)
    PBS
    Yes, for type 2 diabetes
    Notable
    A long shortage (2022 onwards) has now resolved
  5. DiscontinuedExenatide (Byetta, Bydureon)
    How taken
    Twice-daily or weekly injection
    Approved for
    Type 2 diabetes
    Weight loss
    Modest
    Blood sugar
    Lowers HbA1c
    PBS
    No longer available in Australia
    Notable
    The first of the family, based on a hormone found in Gila monster saliva; now largely replaced

For the full weight-loss line-up, including tablets and pills still in trials, see weight-loss medicines compared.

Side effects

Gut side effects are the main ones, worst when starting and after each dose step, and usually settle. Eating smaller meals, stopping when full and going easy on fatty food helps.

Full side-effect list (from the product information)

How often, from the semaglutide (Ozempic) product information. Other GLP-1 medicines are similar; tirzepatide and liraglutide cause slightly more gut upset at weight-loss doses. Bold = serious.

Very common more than 1 in 10

  • Nausea, vomiting, diarrhoea or constipation
  • Tummy pain
  • Headache
  • Tiredness
  • Low blood sugar, if also on insulin or a sulfonylurea

Common 1 in 10 to 1 in 100

  • Dizziness
  • Indigestion, reflux, burping, wind or bloating
  • Gastritis
  • Gallstones
  • Hair thinning
  • Injection-site reactions
  • Low blood pressure
  • Low blood sugar with other diabetes medicines
  • Worsening of diabetic eye disease, if already present

Uncommon 1 in 100 to 1 in 1,000

  • Pancreatitis (inflamed pancreas)
  • Faster heart rate
  • Dizziness on standing
  • Altered taste
  • Raised pancreatic enzymes on blood tests

Rare 1 in 1,000 to 1 in 10,000

  • Anaphylaxis (severe allergic reaction)
  • Angioedema (swelling of the face, lips or throat)

Very rare fewer than 1 in 10,000

  • Sudden vision loss in one eye (NAION)

Frequency not known reported, rate unclear

  • Bowel obstruction

Get help urgently if

Good to know

Common questions

Which GLP-1 medicine causes the most weight loss?

Tirzepatide, on current evidence. In a head-to-head trial, people lost 20.2% of their weight on tirzepatide versus 13.7% on semaglutide over 72 weeks. Individual results vary a lot.

Is “Ozempic face” real?

It isn’t a medical diagnosis. Fast weight loss from any cause, including diet or surgery, shrinks fat in the face and can make skin look looser. It isn’t a special effect of the drug.

Are compounded or online GLP-1 injections safe?

Compounding them has been banned in Australia since October 2024 because the copies aren’t checked for safety, strength or purity. Use only TGA-approved products from a pharmacy.

Does weight come back after stopping a GLP-1 medicine?

Usually, yes. A year after stopping semaglutide in the STEP 1 trial, people had regained about two-thirds of the weight they’d lost.

Can I use GLP-1 medicines in pregnancy?

No. Stop semaglutide at least 2 months and tirzepatide at least 1 month before trying to get pregnant. Tirzepatide can also make the contraceptive pill less reliable.

Information only. Not a recommendation or endorsement of any product. Whether a medicine suits you depends on your health and other medicines, so talk to your doctor or pharmacist. In an emergency, call 000 (Australia) or your local emergency number. From a mobile, 112 works in most countries.

More information

Reviewed 31 October 2026.

Related

maladywise.com/medicines/glp1-medicines/