Starting Mounjaro: What to Expect in Your First Month

Before Your First Injection

You've had your consultation approved, your prescription is dispensed, and the Mounjaro KwikPen has arrived. Here's what to know before you start.

Storage

• Store in the fridge (2-8°C) until first use
• Once in use, you can keep it at room temperature (up to 30°C) for up to 21 days
• Never freeze Mounjaro
• Keep away from direct sunlight

Your Starting Dose

Everyone begins on 2.5mg weekly for the first 4 weeks. This is a sub-therapeutic dose — it's designed to let your body adjust, not to produce maximum weight loss. Don't be discouraged if results seem slow at first.

Week 1: The First Injection

How to Inject

1. Choose your injection site: stomach (5cm from belly button), thigh, or upper arm
2. Clean the area with the alcohol swab provided
3. Attach the needle to the pen
4. Dial the dose
5. Insert the needle at 90° and press the button
6. Hold for 10 seconds before removing
7. Rotate injection sites each week

The needle is very fine — most people say it hurts less than they expected.

What You Might Feel

• Slight soreness at injection site — normal, resolves in a day
• Mild nausea — the most common early side effect
• Reduced appetite — you may notice this within days
• No dramatic changes — the 2.5mg dose is gentle by design

Practical Tips

• Inject on the same day each week (e.g., every Monday evening)
• Take your injection after eating — some people find this reduces nausea
• Stay well hydrated — aim for 2+ litres of water daily
• Eat smaller meals — your stomach is adjusting

Week 2: Adjusting

By week 2, your body is getting used to tirzepatide. Common experiences:

• Appetite changes become noticeable — you feel full sooner at meals
• Nausea may peak then start to improve
• Some people notice 1-2 lbs of weight loss — mostly from eating less
• Food preferences may shift — some people report reduced cravings for fatty or sugary foods

Diet Advice

This is the time to establish good habits that will serve you throughout treatment:

• Prioritise protein — aim for 25-30g per meal (chicken, fish, eggs, Greek yoghurt, lentils). Protein helps preserve muscle mass during weight loss
• Eat slowly — your satiety signals are amplified; give them time to work
• Small, frequent meals rather than 3 large ones
• Reduce ultra-processed foods — you'll likely find them less appealing anyway
• Don't restrict too aggressively — you still need adequate nutrition

Week 3: Finding Your Rhythm

By week 3, most people have established a routine:

• Side effects are typically improving or have resolved
• Eating patterns are shifting — naturally eating less without feeling deprived
• Energy levels should be stable — if you're feeling very fatigued, you may be under-eating
• Weight loss: 1-3 lbs total is typical on the 2.5mg starting dose

Common Concerns at This Stage

"I'm not losing much weight"

Normal. The 2.5mg dose is primarily for tolerability. Real results begin when you increase to 5mg and beyond.

"I feel nauseous after certain foods"

Fatty, greasy, or very rich foods often trigger nausea on GLP-1 medications. Your body is telling you to eat lighter — listen to it.

"I'm constipated"

GLP-1 medications slow gastric emptying, which can slow bowel movements. Increase fibre intake, drink plenty of water, and consider a fibre supplement. Stool softeners can help if needed.

"I feel full very quickly"

This is the medication working. Don't force yourself to eat large meals. Eat to satisfaction, not to finish the plate.

Week 4: Preparing for Dose Escalation

Your first month on 2.5mg is ending. At your next dose, you'll typically increase to 5mg — which is when most people start seeing more significant appetite reduction and weight loss.

What to Expect at 5mg

• Appetite suppression becomes more pronounced
• Nausea may briefly return (usually milder than the first time)
• Weight loss typically accelerates to 1-2 lbs per week
• "Food noise" reduction becomes more noticeable

Month 1 Summary: Realistic Expectations

Essential Supplies

Keep these on hand during your first month:

• Water bottle — hydration is crucial
• Sugar-free ginger sweets — help with nausea
• High-protein snacks — Greek yoghurt, nuts, protein bars
• Fibre supplement — if constipation develops

One Month In: The Bigger Picture

The first month is about adjustment, not dramatic results. You're laying the groundwork for the months ahead. Patients who take the dose escalation slowly and establish good habits in month 1 tend to have better long-term outcomes.

The real transformation typically begins from month 2-3 onwards, as doses increase and your body fully adapts to the medication.

At Roots Pharmacy, our prescribers monitor your progress and adjust dosing accordingly. If you have concerns during your first month, don't hesitate to get in touch.