Types of Weight Loss Medication: Injections, Tablets & GLP-1s

by Burst Health April 14, 2026

Prescription weight loss medications in Australia work through different biological mechanisms and come in different forms. Rather than choosing a specific product yourself, understanding the broad categories of treatment can help you have a more informed conversation with your doctor about what may be clinically appropriate for your situation.

This guide explains how weight loss medications are grouped, what each category involves in practice, and the factors your prescriber will consider. All prescription weight loss medications in Australia are regulated by the Therapeutic Goods Administration (TGA) and require a valid prescription from a registered medical practitioner.

How Weight Loss Medications Are Categorised

There are two useful ways to think about weight loss medications: by how they work in the body (mechanism of action) and by how they are taken (delivery method). These overlap significantly, because different medication classes tend to come in specific forms.

The five main categories of prescription weight loss medication currently available in Australia are:

Appetite suppressants (oral tablets) - act on neurotransmitter systems in the brain to reduce hunger
Lipase inhibitors (oral capsules) - reduce dietary fat absorption in the digestive system
Combination oral medications (tablets) - combine two active ingredients targeting different pathways
GLP-1 receptor agonists (subcutaneous injection) - mimic a gut hormone that signals fullness
Dual-action receptor agonists (subcutaneous injection) - target two hormone receptors (GLP-1 and GIP)

Each of these categories works differently, has a different side effect profile, and involves a different day-to-day experience for the patient. Understanding these differences gives you a practical basis for discussing options with your prescriber.

Oral Medications: Tablets and Capsules

Oral medications are the most familiar form of prescription treatment. They are swallowed, absorbed through the digestive system, and do not require any special storage, injection technique, or medical equipment at home.

Appetite Suppressants (Central Nervous System Agents)

Some oral weight loss medications work by acting on neurotransmitter systems in the brain, primarily noradrenaline. They reduce the sensation of hunger and can make it easier to adhere to a reduced-calorie diet. These are among the oldest class of weight loss medication and have been prescribed in Australia for decades.

In practice, appetite suppressants are typically taken once daily as a capsule, usually in the morning. They are generally prescribed for short-term use (up to 12 weeks at a time) because their effectiveness can diminish with prolonged use and because some carry a risk of dependence.

Common side effects include increased heart rate, elevated blood pressure, difficulty sleeping, dry mouth, and restlessness. Because of their cardiovascular effects, these medications are not suitable for people with uncontrolled high blood pressure, heart disease, or a history of stroke. Some appetite suppressants are classified as Schedule 8 (Controlled Drug) in Australia, which means prescriptions are subject to additional restrictions and cannot be issued for extended periods without review.

For a deeper look at how this class works at a biological level, see our guide to how appetite suppressants work in Australia.

Lipase Inhibitors

Lipase inhibitors take a completely different approach. Rather than affecting appetite or brain chemistry, they work in the digestive system by blocking lipase, the enzyme responsible for breaking down dietary fat. When lipase is inhibited, a portion of the fat from food passes through the body without being absorbed, reducing overall caloric intake from fat.

These medications are taken with meals (typically three times daily with meals that contain fat). They do not require a prescription at the standard dose in Australia - the 120mg strength is available as a Pharmacist Only Medicine (Schedule 3), though your doctor may still recommend it as part of a supervised plan.

The day-to-day experience with lipase inhibitors is distinct from other weight loss medications. Because unabsorbed fat must pass through the digestive system, gastrointestinal side effects are common and can be significant - particularly oily or fatty stools, increased bowel frequency, flatulence, and abdominal discomfort. These effects are directly related to the amount of fat in your diet, so a reduced-fat eating plan is strongly recommended alongside treatment.

Some patients find these side effects help reinforce dietary changes, because eating high-fat meals produces immediate and uncomfortable consequences. Others find the side effects difficult to manage in daily life, particularly in work or social settings. This is a practical consideration worth discussing with your doctor.

Combination Oral Medications

A more recent category of oral treatment combines two active ingredients that work through different pathways. One component may act on appetite centres in the brain (similar to traditional appetite suppressants), while the other addresses cravings or reward-related eating behaviours through a different neurological mechanism.

Combination medications are taken as tablets (typically twice daily at maintenance dose) and involve a dose escalation period during the first few weeks, where the dose is gradually increased to reduce the likelihood of side effects. Common side effects can include nausea, constipation, headache, and dizziness.

Because they involve two active substances, combination medications may interact with a broader range of other medicines. Your prescriber will review your full medication list before considering this category.

Injectable Medications

Injectable weight loss medications are administered via subcutaneous injection - a small injection just beneath the skin, usually in the abdomen, thigh, or upper arm. They use pre-filled pen devices with very fine needles, similar to those used by people with diabetes. Most current injectable treatments are taken once weekly.

If you have not self-injected before, the idea can feel confronting. In practice, the injection pens are designed for home use and do not require medical training. Research on Australian patient experiences with injectable weight loss medications indicates that most patients who were initially hesitant about injections adapted within the first few weeks. The needle is short and thin, and the injection takes a few seconds.

GLP-1 Receptor Agonists

GLP-1 receptor agonists are the most significant class of weight loss medication to emerge in recent years. GLP-1 (glucagon-like peptide-1) is a hormone naturally produced in the gut after eating. It signals fullness to the brain, slows the rate at which the stomach empties, and helps regulate blood sugar levels.

Medications in this class mimic or enhance the action of natural GLP-1. The result is that meals feel more satisfying, hunger between meals is reduced, and the overall drive to eat is lower. Unlike appetite suppressants that act on stimulant-type brain pathways, GLP-1 receptor agonists work through the body's own satiety system.

In practice, a GLP-1 receptor agonist is administered as a once-weekly subcutaneous injection using a pre-filled pen. Treatment begins at a low dose, which is increased gradually over several weeks (typically 16 to 20 weeks to reach the full maintenance dose). This slow escalation is important for minimising side effects, particularly nausea.

Common side effects include:

Nausea - most common during dose escalation, often improving over time
Vomiting and diarrhoea - more likely in the early weeks
Constipation - can occur at any stage of treatment
Reduced appetite - which is part of the intended mechanism but can feel uncomfortable initially
Injection site reactions - minor redness or swelling at the injection point

GLP-1 receptor agonists were originally developed for the management of type 2 diabetes. Regulatory bodies, including the TGA, have since approved specific formulations at specific doses for use in weight management. Their use for weight loss requires a separate clinical assessment from their use in diabetes treatment.

For more on this medication class, see our guide to GLP-1 medications for Australians.

Dual-Action Receptor Agonists (GLP-1/GIP)

The newest category of injectable weight loss medication targets two hormone receptors rather than one. These dual-action treatments activate both GLP-1 receptors and GIP (glucose-dependent insulinotropic polypeptide) receptors, potentially providing a stronger combined effect on appetite regulation, blood sugar control, and metabolic function.

Like GLP-1 receptor agonists, dual-action medications are administered as a once-weekly subcutaneous injection and involve a dose escalation period. The side effect profile is similar (nausea, gastrointestinal effects, reduced appetite), though the escalation schedule and available dose levels differ.

Dual-action receptor agonists are a relatively recent addition to the Australian treatment landscape. Long-term data on this newer class continues to be gathered through ongoing clinical research. As with all prescription medications, their suitability depends on individual clinical assessment by a qualified prescriber.

What Each Type Involves Day-to-Day

Beyond the clinical differences, each medication category creates a different daily experience. This practical dimension matters because you will be managing your treatment alongside work, travel, social life, and other routines.

Storage and Handling

Oral medications (tablets and capsules) are stored at room temperature and are straightforward to transport. You can carry them in a bag or pill organiser without special equipment.

Injectable medications require refrigeration before first use (typically 2-8 degrees Celsius). Once in use, most pen devices can be stored at room temperature (below 30 degrees Celsius) for a limited period, usually up to 28 days. This is an important consideration for travel - you may need a cool bag or insulated pouch for longer trips, and you should check airline regulations for travelling with injection devices and medication that requires temperature control.

Sharps Disposal

If you use injectable medication, you will need a sharps container for disposing of used pen needles. These are available from pharmacies, and many Australian councils and pharmacies provide free sharps disposal services. Your pharmacist can advise on local arrangements.

Frequency and Routine

Oral medications may be taken once daily (appetite suppressants), twice daily (some combination medications), or three times daily with meals (lipase inhibitors). Injectable medications are typically administered once weekly on the same day each week, at any time of day.

Some patients find a weekly injection easier to remember and incorporate into their routine than daily tablets. Others prefer the familiarity and simplicity of oral medication. Neither approach is inherently better - it depends on what works for your life.

How Your Doctor Decides Which Type May Be Appropriate

No single type of weight loss medication is universally suitable. Your doctor will consider a range of clinical and practical factors when assessing whether medication is appropriate and, if so, which category to consider. These typically include:

Your body mass index (BMI) and weight history - most prescribing guidelines require a BMI of 30 or above (or 27+ with weight-related health conditions)
Existing medical conditions - cardiovascular disease, type 2 diabetes, gastrointestinal conditions, mental health history, and other diagnoses all influence which categories are safe for you
Current medications - potential drug interactions vary across categories
Previous weight management approaches - including any prior use of weight loss medication and the outcomes
Treatment duration - some categories are intended for short-term use, others for ongoing management
Cost and access - injectable medications tend to be more expensive than oral options, and not all medications are subsidised through the PBS (see our guide to weight loss medication costs in Australia)
Your preferences and lifestyle - tolerance for injections, ability to manage cold storage, meal timing requirements

Weight loss medication is not a standalone treatment. In all cases, prescription medication is intended to be used alongside dietary changes, increased physical activity, and behavioural support. Your doctor may also recommend regular monitoring appointments to assess how you are responding to treatment.

Regulation and Scheduling in Australia

All prescription weight loss medications in Australia are classified under the Standard for the Uniform Scheduling of Medicines and Poisons (SUSMP), maintained by the TGA. The scheduling determines how a medication can be prescribed, dispensed, and accessed:

Schedule 3 (Pharmacist Only Medicine) - some lipase inhibitors at standard doses are available from a pharmacist without a prescription, though a consultation with the pharmacist is required
Schedule 4 (Prescription Only Medicine) - most weight loss medications fall here, including all GLP-1 receptor agonists, dual-action agonists, and combination oral medications. A valid prescription from a registered medical practitioner is required
Schedule 8 (Controlled Drug) - some appetite suppressants carry additional restrictions due to a higher risk of misuse or dependence. Prescriptions for Schedule 8 medications have stricter limits on quantity and repeats

These classifications exist to protect patient safety and ensure that medications are only prescribed after proper clinical assessment. For more on the prescription process, see our guide to how to get weight loss medication in Australia.

The Australian Weight Loss Medication Landscape in 2026

The weight loss medication landscape in Australia has changed significantly in recent years, and several developments are relevant as of early 2026:

Daily GLP-1 injections discontinued - a daily injectable GLP-1 receptor agonist was discontinued from the Australian market in late 2025. Weekly injectable options remain available
PBS listing under review - in January 2026, the Pharmaceutical Benefits Advisory Committee (PBAC) recommended a weekly GLP-1 receptor agonist for PBS subsidy for a specific patient group (those with a high BMI and established cardiovascular disease). Price negotiations are ongoing, and no listing date has been confirmed
Compounding restrictions - the TGA has tightened regulations around compounded weight loss preparations, with enforcement actions against providers offering non-TGA-approved compounded versions of prescription medications
New formulations in development - oral versions of GLP-1 receptor agonists are in late-stage clinical trials internationally, which could eventually change the injection-vs-tablet landscape

These developments mean the options and costs available to Australian patients continue to evolve. Your prescriber will have the most current information about what is available and accessible at the time of your consultation.

For more on recent developments, see our article on new weight loss medications in Australia.

Questions to Discuss with Your Doctor

If you are considering whether prescription weight loss medication may be relevant to your health goals, these questions may help guide a productive conversation:

Based on my health profile, am I a candidate for prescription weight loss medication?
Which category of medication would you consider for my situation, and why that type rather than another?
What does treatment look like in the first month - dose escalation, monitoring, side effects to expect?
How long would treatment typically last, and what happens if or when I stop?
Are there interactions with any of my current medications or conditions?
What are the costs involved, and is there a PBS-subsidised option that suits my situation?

Your prescriber is the most reliable source of advice about which treatment approach, if any, is appropriate for your individual circumstances. Weight management is a long-term process, and medication is one component of a broader clinical plan.

Frequently Asked Questions

What is the difference between weight loss injections and tablets?

The differences go beyond how you take them. Injectable treatments in Australia are primarily GLP-1 receptor agonists or dual-action receptor agonists - they mimic gut hormones that control appetite and are taken once weekly. Oral treatments include appetite suppressants (daily), lipase inhibitors (with meals), and combination medications (twice daily). Each category works through a different biological mechanism, carries different side effects, and has different cost and storage requirements. Your doctor will determine which form and mechanism are most appropriate based on your health profile.

Do I need a prescription for weight loss medication in Australia?

Almost all weight loss medications discussed in this article require a valid prescription from a registered Australian medical practitioner. The one exception is lipase inhibitors at standard dose, which are available as a Pharmacist Only Medicine (Schedule 3) - meaning you can obtain them from a pharmacist after a consultation, without a doctor's prescription. All other categories require a prescription.

Can I switch from one type of weight loss medication to another?

Yes, but only under medical supervision. If one category is not effective, causes unacceptable side effects, or is not suitable for another reason, your prescriber may consider switching to a different category. This is not uncommon - finding the right treatment sometimes involves trying more than one approach. Your doctor will manage the transition, including any washout period needed between medications.

Are weight loss injections more effective than tablets?

Clinical outcomes vary significantly between individuals, and direct comparisons between medication categories are not straightforward because each works through different mechanisms in different patient populations. Published clinical trial data exists for each category, and your prescriber can discuss the evidence relevant to your specific health profile. What works well for one person may not be the best option for another.

What happens when you stop taking weight loss medication?

Weight regain after stopping medication is a well-documented clinical reality across all categories of weight loss treatment. The degree of regain varies between individuals and depends on factors including the type of medication used, how long it was taken, and whether lifestyle changes (diet and exercise) have been sustained. This is an important topic to discuss with your doctor before starting treatment, so you can plan for what long-term weight management looks like beyond medication.