Drug companion protocol

Semaglutide (Wegovy)

Prescription only

GLP-1 receptor agonist

Also known as: Wegovy

A GLP-1 receptor agonist prescribed for chronic weight management in adults.

Quickstart Highlights

Drug class: GLP-1 receptor agonist
Route: Subcutaneous injection
Schedule: Weekly subcutaneous injection
Evidence score: 85

Quickstart highlights

💉Subcutaneous injection
🔬GLP-1 receptor agonist
🖊️Pre-filled autoinjector pen
📋Prescription required

General information only — not medical advice.Always follow your prescriber's instructions.

How this works

Mechanism of action and pharmacokinetic profile from published data.

Semaglutide is a GLP-1 (glucagon-like peptide-1) receptor agonist — a synthetic analogue of the naturally occurring gut hormone GLP-1. It binds to GLP-1 receptors in the pancreas, brain, and gut, which increases glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and reduces appetite via central hypothalamic pathways. The 2.4 mg once-weekly dose used in Wegovy delivers higher receptor exposure than the lower doses used for type 2 diabetes, producing larger and more sustained reductions in appetite and body weight.

Time to peak (Tmax): 24–72 hours after a subcutaneous injection — peak concentration typically occurs 1–3 days post-dose.
Clearance: Degraded via proteolytic cleavage and fatty acid oxidation — not primarily renally or hepatically cleared as an intact molecule. Dose adjustment for mild-moderate renal impairment is not required.
Elimination half-life: Approximately 1 week (7 days), which is why it is dosed once weekly.
Bioavailability: High systemic exposure after subcutaneous injection; approximately 89% bound to albumin in plasma, which contributes to the long half-life.

Injection guide

Supplies, step-by-step technique, safety notes, and AU sharps disposal.

Supplies needed

◦Your prescribed Wegovy pen (correct dose) — Check that the dose on the pen label matches what your prescriber ordered. Wegovy comes in five fixed-dose strengths — 0.25 mg, 0.5 mg, 1.0 mg, 1.7 mg, and 2.4 mg.
◦A new pen needle — NovoFine Plus 4 mm × 32G or equivalent are commonly used. Use a new needle for every injection — reusing blunts the needle and increases injection-site reactions.
◦Alcohol swab — To clean the injection site before injecting.
◦Sharps disposal container — A rigid, puncture-resistant container for used needles. Available from pharmacies; mail-back programs are listed under Disposal below.

Step-by-step

1Wash your hands
Wash with soap and water and dry thoroughly before handling the pen or needle.
2Remove the pen from the fridge
Take the pen out of the fridge 30 minutes before injecting. Injecting cold medicine can sting more and slow absorption.
3Check the pen
Inspect the liquid through the window — it should be clear, colourless, and free of particles. Check the expiry date. Do not use if it looks cloudy or discoloured.
4Attach a new pen needle
Remove the paper tab from the outer needle cap. Push and twist the needle onto the pen until it is secure. Pull off the outer needle cap (keep it for later removal). Pull off the inner needle cap and discard it.
5Choose your injection site
Inject into the fatty tissue of your abdomen (at least 5 cm from your navel), the front of your upper thigh, or your upper arm. Rotate sites within each area each week — do not inject in the same spot consecutively.
6Clean the site
Wipe the area with the alcohol swab and let it dry fully before injecting.
7Inject
Hold the pen at 90° to your skin. Press the pen firmly against your skin and press the injection button. Hold for 6 seconds after pressing — you will hear a click when the injection starts. A second click or colour change in the window confirms the full dose was delivered.
8Remove and dispose of the needle
Pull the pen straight away from the skin. Place the outer cap back on the needle using a one-hand scoop technique — do not recap with two hands. Unscrew the needle and place it directly into your sharps container.
9Store the pen
Return the used pen to the fridge if it has doses remaining. If this was a single-dose pen, dispose of it in your sharps container.

Important notes

!Never inject into a vein or muscle
Subcutaneous injection (into the fatty layer under the skin) is the correct route. Injecting into a vein or muscle changes how the medicine is absorbed and can cause serious reactions.
!Never share your pen with anyone else
Even with a new needle, blood-borne infections including HIV and hepatitis can be transmitted via shared pens. Your pen is for your use only.
!Rotate injection sites every week
Using the same spot repeatedly causes lipohypertrophy — a hardened fatty lump under the skin. Injecting into a lump reduces absorption unpredictably.
!Do not inject into scar tissue, bruises, or broken skin
!If you miss a dose by more than 5 days, skip it
Take your next dose on your regular scheduled day. Do not double-dose to make up for a missed one.
!Tell all healthcare providers you are using Wegovy
Slowed gastric emptying affects fasting requirements for procedures and the absorption of other oral medicines.

Sharps disposal

◦Use a sharps disposal container — Place used needles and pens directly into a rigid, puncture-resistant sharps container. Do not place loose needles in household rubbish or recycling.
◦NestSafe sharps mail-back program (Australia) — Free household sharps mail-back program. Collect a free mail-back kit from participating pharmacies or via nestsafe.com.au. Seal and post when full — no charge.
◦EnviroSafe sharps disposal (Australia) — Another AU mail-back option available through participating pharmacies. Kits are provided at no cost to patients.
◦Community pharmacy drop-off — Many Australian pharmacies accept filled sharps containers for disposal. Ask your dispensing pharmacy if they offer this service.

Clinical Benefits & Side Effects

Observed outcomes, adverse effects, and lifecycle considerations from published trial data.

Benefits

Week 0

Starting your first injection

Wegovy begins at 0.25 mg weekly for the first four weeks — lower than the long-term target dose. This period is about tolerability, not weight loss. Many people notice reduced appetite within the first week.

Week 1

First injection — taking the first step

You've taken your first dose — well done! This week is all about getting familiar with the injection routine. You may feel little to no effect yet, and that's completely normal at this low starting dose.

Week 2

Early signals — body beginning to notice

Some people start to notice mild nausea, particularly after eating, or a slightly reduced appetite. Others feel no different at all — both experiences are common. Take it easy and be kind to yourself as your body adjusts.

Week 3

Navigating nausea — the most common hurdle

Nausea is most frequently reported around weeks 2–4 and can catch people off guard. Eating smaller meals, slowing down at mealtimes, and avoiding rich or fatty foods can help significantly. Hang in there — for most people, this eases with time.

Week 4

Completing your first month — building consistency

You've completed your first month — a real milestone! Weight changes may be minimal or not yet visible, and that's expected at this early stage. The focus right now is on consistency and letting your body adapt to the medication.

Week 4

First dose escalation

The dose steps up to 0.5 mg weekly in weeks 5–8. Some people experience mild nausea or reduced appetite around each dose increase — this usually settles within a week or two.

Week 5

Dose escalation begins — a new adjustment phase

Your prescriber may increase your dose around this point, which can bring a fresh wave of adjustment side effects, including nausea or fatigue. This is a normal part of the escalation process — follow your prescriber's instructions on when and how to increase your dose.

Week 6

Appetite suppression becoming more noticeable

Many people begin to notice a meaningful reduction in hunger and food cravings around this week. You may find yourself feeling full faster or simply less interested in snacking. This is the medication working — use it as an opportunity to practise mindful, nourishing eating.

Side effects

◦Increased heart rate(mild)

Small average increase; generally not clinically significant

◦Abdominal pain(mild)

~20%

◦Fatigue(mild)

Reported; often resolves

◦Vomiting(mild-to-moderate)

~24%

◦Injection-site reaction(mild)

Mild; generally transient

◦Diarrhoea(mild-to-moderate)

~30%

◦Constipation(mild)

~24%

◦Dizziness(mild)

Reported; often associated with dehydration

◦Headache(mild)

Common during early weeks

◦Nausea(mild-to-moderate)

~44%

Lifecycle factors

Nausea during escalation is usually temporary

Most nausea with Wegovy occurs during dose-escalation weeks, then improves. Eating bland, small amounts, avoiding greasy foods, and staying upright after meals helps. If nausea is severe or persistent, contact your prescriber — they may hold your dose rather than escalate.

Tell your prescriber about any vomiting

Severe or repeated vomiting can cause dehydration and, if prolonged, may indicate a rare adverse reaction requiring evaluation. Contact your prescriber if vomiting lasts more than a day or two at a dose.

Manage nausea with small, practical strategies

If nausea hits, try plain crackers, dry toast, or a small piece of banana to settle your stomach. Cold or room-temperature foods are often better tolerated than hot, strongly-smelling meals. Ginger tea or ginger chews (available at most Australian supermarkets and health food stores) can also provide relief. Speak to your prescriber if nausea is severe or persistent.

Important note

This content is intended for therapeutic educational purposes only and does not constitute medical advice, diagnosis, or treatment. All information presented is based on published clinical trial data. Always follow your prescriber's instructions.

Nutrition & practical guidance

Food, hydration, and adherence tips compiled from trial data and clinical companion content.

Food and hydration

✅ Prefer

Lean proteins (chicken breast, canned tuna, eggs, reduced-fat Greek yoghurt)Lean protein at every mealCooked or steamed non-starchy vegetables (zucchini, carrots, broccoli, spinach)Non-starchy vegetablesWholegrains in small portions (brown rice, wholegrain bread, oats)Slow-digesting carbohydratesLegumes (lentils, chickpeas, four-bean mix)Soft, easily digested fruits (banana, tinned peaches in juice, melon)Small, frequent meals

⚠️ Limit

High-fat takeaway and fast food (burgers, chips, fried chicken)Large, high-fat mealsSugary drinks and fruit juices

Adherence tips

administration

Rotate your injection sites consistently

Inject into the fatty tissue of your abdomen (at least 5 cm from your belly button), outer thigh, or upper arm — and rotate sites each week to prevent skin irritation or lumps (lipohypertrophy). Keep a simple note in your phone to track which site you used last. Always follow your prescriber's instructions on administration technique.

administration

Use the same day each week, at a consistent time

A weekly rhythm is easier to maintain than guessing. Set a phone reminder on your chosen injection day. If you miss a dose by fewer than five days, take it as soon as you remember. If more than five days have passed, skip that dose and resume on your next scheduled day.

administration

Store and prepare your pen correctly

Wegovy pens should be stored in the refrigerator (2–8°C) but **not** in the freezer. Before injecting, let the pen sit at room temperature for 15–30 minutes — a cold injection can be more uncomfortable. Check the pen window to confirm the liquid is clear before each use.

timing

Pick a consistent injection day and stick to it

Choosing the same day each week (e.g., every Sunday morning) helps build a reliable routine and reduces the chance of a forgotten dose. Some people prefer injecting in the evening if they find nausea is worse in the mornings. Set a recurring phone reminder as a backup.

nutrition

Protein-first plating

When your appetite is small, lead every meal with protein — chicken, fish, legumes, eggs, tofu — before eating carbs or vegetables. This helps you meet protein targets (roughly 1.2–1.5 g/kg body weight) even with reduced overall intake.

timing

Time your meals around injection day

Nausea tends to peak in the 12–24 hours after your injection. On injection day, consider eating your lightest, most easily digested meals — think plain toast, scrambled eggs, or a small bowl of oats — rather than a heavy dinner. Planning ahead makes those first days of each week much more manageable.

administration

Rotate injection sites

Use the abdomen (at least 5 cm from the navel), thigh, or upper arm. Rotating sites within each area and not injecting into sore, bruised, or hardened skin reduces injection-site reactions.

nutrition

Prioritise protein at every meal

Aim for a source of protein at every meal — such as eggs, Greek yoghurt, tinned fish, legumes, or lean chicken. When overall food intake is lower, protein helps protect muscle mass and keeps you feeling satisfied. Targeting roughly 25–30 g of protein per meal is a helpful general goal.

nutrition

Eat smaller portions, more slowly

Semaglutide slows the rate at which your stomach empties, so large or fast-eaten meals can cause significant discomfort. Try using a smaller plate, putting your fork down between bites, and aiming to take at least 15–20 minutes per meal. Stop eating when you feel satisfied — not full.

mindset

Weight loss may slow before plateauing

The rate of loss typically slows as your body weight stabilises at a new set point. A slower rate is not a sign of treatment failure — STEP 5 showed continued effect through 2 years with ongoing treatment. Do not self-escalate dose if progress slows.

hydration

Drink between meals, not during them

Drinking large amounts of fluid with meals can contribute to a feeling of fullness and bloating. Instead, sip water steadily between meals throughout the day. Keeping a 500 mL water bottle visible on your desk or bench is a simple cue to stay on track with your 2–2.5 L daily goal.

exercise

Start moving — even a short daily walk counts

You don't need to overhaul your exercise routine overnight. Even a 20–30 minute walk each day supports weight management, improves mood, and helps with digestion. As energy improves in weeks 6–12, gradually add strength-based activity (like bodyweight exercises or resistance bands) to help preserve muscle.

exercise

Pair resistance training with your reduced appetite

Because semaglutide reduces overall food intake, some muscle loss can occur without adequate protein and resistance exercise. Aim to include at least 2 sessions of light resistance training per week — this doesn't need to be a gym; home bodyweight exercises are effective. This is one of the most impactful habits you can build during this journey.

sleep

Protect your sleep — it directly affects weight management

Poor sleep increases hunger hormones and can make cravings harder to manage, even with appetite suppression from medication. Aim for 7–9 hours per night and try to go to bed and wake at consistent times. If nausea or discomfort is disturbing your sleep, sleeping slightly elevated (with an extra pillow) may help.

mindset

Track non-scale victories alongside your weight

The number on the scale tells only part of the story. Keep a simple weekly note of other changes — more energy, clothes fitting differently, improved sleep, fewer cravings, or a longer walk than last month. These markers are just as meaningful as kilograms and will keep you motivated through weeks when the scale doesn't move.

mindset

Expect progress to be non-linear — and that's okay

Weight loss on semaglutide is rarely a straight downward line. Plateaus and weeks with no change are completely normal and don't mean the medication isn't working. Focus on your consistent habits rather than the week-to-week number. Comparing your week 12 self to your week 1 self — not to anyone else's journey — is the most useful frame of reference.

mindset

Be honest with your prescriber about side effects

If side effects are making it hard to eat, sleep, or function, let your prescriber know — there are options available and your prescriber can adjust your plan. You don't need to push through alone. Open communication with your care team is one of the most important things you can do throughout this journey. Always follow your prescriber's instructions about your dosing schedule.

Safety and interactions

Share this information with your prescriber for personalised care decisions.

Who should not take this

Wegovy is a prescription medicine. Do not use if you have: • A personal or family history of medullary thyroid carcinoma (MTC) • Multiple endocrine neoplasia syndrome type 2 (MEN2) • A known allergy or hypersensitivity to semaglutide or any ingredient in the product • Had serious hypersensitivity reactions to other GLP-1 receptor agonists Use with caution (discuss with your prescriber) if you have: • A history of pancreatitis • Diabetic retinopathy — rapid glucose improvement can transiently worsen retinal changes • Severe kidney or liver disease • Active or recent eating disorder Not recommended during pregnancy or breastfeeding. Always provide your full medical history to your prescriber before starting.

Known interactions

Insulin and insulin secretagogues (e.g. sulfonylureas)
significant
Increased risk of hypoglycaemia. Your prescriber may reduce your insulin or sulfonylurea dose when starting or escalating Wegovy.
Oral contraceptives
moderate
Semaglutide slows gastric emptying, which may transiently reduce the absorption of oral contraceptives during dose escalation. Consider additional non-hormonal contraception around dose changes.
Medicines with narrow therapeutic index (e.g. warfarin, ciclosporin, some anti-epileptics)
moderate
Delayed gastric emptying can alter the absorption rate of orally administered medicines. Monitoring of drug levels or INR may be warranted.
Alcohol
moderate
Alcohol can worsen nausea (already a common GLP-1 effect) and increase the risk of hypoglycaemia.

Storage and handling

Store the Wegovy pen in the refrigerator at 2–8°C (36–46°F) until first use. • After first use, or if stored out of the refrigerator: use within 28 days, keeping below 30°C and away from direct heat and light. • Never freeze the pen — freezing destroys the active molecule. • Keep the cap on the pen when not in use. • Store away from children. • Do not use the pen if it has been dropped, damaged, or if the liquid looks cloudy, discoloured, or contains particles.

Research evidence

Published studies connected to this peptide with dosage and outcomes context.

Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT)

Human trial · 2023 · New England Journal of Medicine · n=17604 · Adults with overweight or obesity, established cardiovascular disease, without type 2 diabetes at baseline

17,604 adults with established cardiovascular disease were randomised to semaglutide 2.4 mg weekly or placebo over ~33 months. Semaglutide reduced the risk of major adverse cardiovascular events (MACE — cardiovascular death, non-fatal MI, or non-fatal stroke) by 20% versus placebo (HR 0.80, 95% CI 0.72–0.90).

Reported outcomes

weight_loss: Mean body-weight reduction of 9.4% versus 0.9% with placebo at ~33 months. (Secondary)
cardiovascular: 20% relative risk reduction in MACE (cardiovascular death, non-fatal MI, or non-fatal stroke) versus placebo over ~33 months. (Primary outcome)

DOI: 10.1056/NEJMoa2307563 ↗

Two-Year Effects of Semaglutide in Adults with Overweight or Obesity (STEP 5)

Human trial · 2022 · Nature Medicine · n=304 · Adults with obesity or overweight plus comorbidity, without type 2 diabetes

304 adults received once-weekly semaglutide 2.4 mg or placebo for 104 weeks (2 years). Mean body-weight change was −15.2% with semaglutide versus −2.6% with placebo. Cardiometabolic risk markers improved across lipids, blood pressure, and inflammatory markers.

Reported outcomes

cardiometabolic: Sustained improvements in lipids, blood pressure, and CRP (inflammatory marker) over 2 years. (Secondary)
weight_loss: Mean body-weight reduction of 15.2% at 104 weeks (2 years) on 2.4 mg weekly, versus 2.6% with placebo. (Primary outcome)

DOI: 10.1038/s41591-022-01893-7 ↗

Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1)

Human trial · 2021 · New England Journal of Medicine · n=1961 · Adults with obesity (BMI ≥30) or overweight (BMI ≥27) with ≥1 weight-related condition, without type 2 diabetes

1961 adults were randomised to once-weekly subcutaneous semaglutide 2.4 mg or placebo for 68 weeks, alongside lifestyle intervention. Mean body-weight change was −14.9% with semaglutide versus −2.4% with placebo; 86.4% of semaglutide participants achieved ≥5% weight loss. Nausea and diarrhoea were the most common adverse events.

Reported outcomes

cardiometabolic: Improvements in waist circumference, systolic blood pressure, fasting glucose, HbA1c, and lipids versus placebo. (Secondary)
responder_rate: 86.4% of semaglutide participants achieved ≥5% body-weight loss; 69.1% achieved ≥10%. (Secondary)
weight_loss: Mean body-weight reduction of 14.9% at 68 weeks on 2.4 mg weekly, versus 2.4% with placebo. (Primary outcome)

Reported dosage

0.25 mg · once weekly subcutaneous · 4 weeks — Starting dose — tolerability run-in only; not a therapeutic dose.
2.4 mg · once weekly subcutaneous · 52 weeks — Target maintenance dose — primary endpoint dose.
1.7 mg · once weekly subcutaneous · 4 weeks — Escalation step 4.
0.5 mg · once weekly subcutaneous · 4 weeks — Escalation step 2.
1 mg · once weekly subcutaneous · 4 weeks — Escalation step 3.

DOI: 10.1056/NEJMoa2032183 ↗

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