Weight Loss Injection Dosages Explained

Whether you’re currently taking or considering weight loss medication like Wegovy (semaglutide) or Mounjaro (tirzepatide), understanding how dosing works is key. These medications help reduce appetite and enhance satiety, and their effectiveness is optimised through a gradual increase in dosage, a process known as titration.

 In this guide, we’ll compare the typical weight loss injection dosages, explain why a stepped approach is recommended, and link you to specific guidance depending on which medication you're using.

 This is what our Chief Medical Officer, Dr. Charlotte Norton says:
“You must always start on the lowest dose when beginning a GLP-1 medication. It gives your gut a chance to adapt, reduces side effects, and helps you stay on track for long-term weight loss.”

Weight loss pens come in different doses because your body needs time to adjust. Both Wegovy and Mounjaro start at the lowest dose and gradually increase over several weeks, a process called titration. This allows your body to build tolerance to the medication while still benefiting from its appetite-reducing effects. Starting too high too soon can lead to uncomfortable side effects such as nausea or digestive issues.

Like with many other medications, weight loss injections follow structured dose escalation plans, known as titration schedules. While both begin at a low starting dose to minimise side effects, their step-up intervals, final doses, and active ingredients differ slightly. Here’s a quick comparison to help you understand how the two options are typically scheduled:

Note: Your specific schedule may vary depending on how your body responds, and your doctor’s recommendations. Explore the full dosage schedules for your specific medication below.

How will I know which dose to start on when I begin my journey?

If you’re beginning your journey with weight loss injections like Mounjaro or Wegovy, the answer is clear: you must always start on the lowest dose.

As Dr. Charlotte explains, these medications work by reducing appetite and slowing digestion, so it’s important to give your body, especially your gut, time to adjust. That’s why the first pen contains four low-dose injections, designed to be taken once a week over four weeks. This starter dose is essential for building tolerance and minimising side effects.

The good news? You can begin losing weight effectively from this starting dose. There’s no need to rush to the top strength. Whether or not you move up after the first month depends on:

• How well you're tolerating the medication.
• How in control you feel of your appetite.
• Whether you’re seeing consistent weight loss.

Do I Decide When to Go Up a Dose?

If you're wondering whether you can decide on your own when to increase your weight loss injection dose, the answer depends on how you're accessing your treatment. At The Slimming Clinic, you’re never left to figure it out alone.

When you request a prescription through our online pharmacy, our health assessment form will ask specific questions about how you're responding to your current dose, covering everything from weight loss progress to side effects. That information is then reviewed by one of our GMC-registered doctors, who will help determine if you're ready to move up.