Weight loss pen treatment: how it works
A SengMed guide, reviewed by our clinical team
The “weight loss pen” is the device many people picture when they hear about modern medical weight loss. It’s a pre-filled injection pen containing a GLP-1 medication. This guide explains what the pen is, how treatment works, and what to expect, in plain language.
This guide is general information, not medical advice. Whether weight loss pen treatment is suitable for you is a decision for an MOH-licensed doctor based on your health.
What is a weight loss pen?
A weight loss pen is a small, pre-filled injector that delivers a measured dose of a GLP-1 medication (such as semaglutide or tirzepatide) just under the skin. It looks similar to an insulin pen and is designed for easy self-administration at home.
The pen itself isn’t the treatment, the medication inside it is. The pen is simply a convenient, accurate way to deliver it.
How the treatment works
GLP-1 medication mimics a natural gut hormone that controls appetite and fullness. With regular dosing, most people find they:
- Feel hungry less often.
- Feel full sooner and with smaller portions.
- Have fewer cravings and steadier energy.
Over time, eating less feels far more manageable, which supports gradual, sustainable weight loss alongside healthy habits.
What a course of treatment looks like
- Assessment. A licensed doctor reviews your health history and BMI to confirm whether treatment is appropriate.
- Starting dose. Treatment begins at a low dose. This “titration” gives your body time to adjust and keeps side effects mild.
- Weekly injections. Most pens are used once a week. You rotate the injection site (abdomen, thigh, or upper arm).
- Dose increases. Your doctor steps the dose up over several weeks, guided by how you respond.
- Ongoing review. Regular check-ins track your progress and adjust the plan.
See our companion guides on how to inject and your first 6 weeks for the practical detail.
What results to expect
Results vary from person to person. Many patients lose a meaningful proportion of their body weight over several months of consistent, doctor-guided treatment. Progress is usually gradual rather than sudden, and habits around food, movement, and sleep make a real difference to the outcome.
Side effects and safety
The most common side effects are digestive, mild nausea, constipation, or reduced appetite, and are usually most noticeable when starting or increasing the dose. Starting low and increasing slowly helps. A doctor screens your health first, because the treatment isn’t suitable for everyone.
What it costs in Singapore
With SengMed, weight loss pen treatment is offered on a monthly plan with no membership fee or lock-in. The plan covers your online doctor consultation, ongoing care, and free islandwide delivery; medication cost varies by treatment. Indicative pricing is shown on our home page, and your final plan is confirmed by your doctor.
Getting started
The first step is a health assessment with a licensed doctor. With SengMed you can complete this online, and an MOH-licensed doctor will advise whether weight loss pen treatment is right for you.