Introduction
Weight loss injections like Wegovy, Saxenda, Mounjaro, Semaglutide, Tirzepatide are changing lives by helping people regulate appetite, manage blood sugar, and lose weight in a sustainable way. But for many, the idea of giving yourself an injection can feel intimidating.
Don’t worry—we’ve got you covered. This guide walks you through exactly how to administer weight loss injections safely, effectively, and confidently.
1. Understand Your Medication
Before you pick up the pen or vial, know what you’re working with.
Most Common Weight Loss Injectables:
- Wegovy (semaglutide): Injected subcutaneously once a week
- Mounjaro (tirzepatide): Injected subcutaneously once a week
Your healthcare provider will guide you on dosage and how to ramp up safely over time.
Here’s a simple comparison chart showing the typical dosing schedules for Wegovy and Mounjaro:
| Week | Wegovy (Semaglutide) | Mounjaro (Tirzepatide) |
| 1-4 | 0.25 mg weekly | 2.5 mg weekly |
| 5-8 | 0.5 mg weekly | 5 mg weekly |
| 9-12 | 1 mg weekly | 7.5 mg weekly |
| 13-16 | 1.7 mg weekly | 10 mg weekly |
| 17+ | 2.4 mg weekly (maintenance) | 12.5 mg → 15 mg weekly (maintenance range) |
2. Prep Like a Pro
Here’s what to do before injecting:
- Wash your hands.
- Check that the medication is:
- Clear and free of particles
- Not expired
- At the correct dose. If you are using an insulin syringe to draw medication from a vial, note that 1ml is equal to 100 units. Pay special attention to the concentration of the medication in milligram per milliliter (mg/ml). This can vary if using compounded medications. The number of units from different compounding pharmacies should not be applied to a medication from a different pharmacy without consulting with a pharmacist.
- Let refrigerated pens sit for a few minutes to reach room temperature. This reduces the injection site pain.
- If using a pen, attach a new needle every time.
- Use alcohol pad to wipe the injection site (your skin) and a separate pad to wipe the top of the vial prior to pulling medication from vial.
3. Choose Your Injection Site
Weight loss injectables are subcutaneous, meaning they go just under the skin.
Best spots:
- Stomach (abdomen) – stay at least 2 inches from the belly button
- Thigh – front part of your upper leg or drop both hands to the side of your thigh. Where your palm rest would be an alternative injection site.
- Upper arm – only if someone else helps you
Rotate injection sites each time to avoid skin irritation.
Diagram of recommended injection sites on the body
4. Inject with Confidence
Follow these steps to get it right every time:
- Clean the skin with an alcohol swab.
- Gently pinch the skin at the injection site.
- Insert the needle at a 90° angle (or 45° if you’re very lean).
- Press the button or plunger and hold for 5–10 seconds.
- Remove the needle and safely discard it in a sharps container.
Never reuse needles or share your injection device.
5. Stick to the Schedule
Consistency is key with weight loss injectables.
- Wegovy: Weekly on the same day
- Saxenda: Daily at the same time
- Mounjaro: Weekly
- Semaglutide: Weekly
- Tirzepatide: Weekly
Pro tip: Set a reminder on your phone or use a medication tracking app.
6. Know the Side Effects
Common (usually temporary):
- Nausea and Vomiting
- Bloating
- Fatigue
- Diarrhea or constipation
- Injection site reactions like redness
Serious (rare, but important):
- Severe abdominal pain
- Signs of pancreatitis or gallbladder issues
- Allergic reactions
Contact your doctor immediately if you experience severe or unusual symptoms.
Storage & Safety Tips
- Store pens and vials in the refrigerator unless instructed otherwise.
- Use a sharps container for disposal.
- Never freeze the pen or expose it to high heat.
- Multidose vials should be discarded 28 days after first us.
How Much Weight Should I Expect to Lose?
Below is the weight loss from base weight observed at 3, 6, and 12 months after starting weight loss injectables:
| Duration of Therapy in Month | Semaglutide Weight loss percent | Tirzepatide Weight loss percent |
| 3 | -3.6% | -5.9% |
| 6 | -5.8% | -10.1% |
| 12 | -8.3% | -15.3% |
Final Takeaway
Learning to self-inject can feel overwhelming at first—but with practice, it becomes second nature. These medications can help you make real progress on your weight loss journey, especially when combined with healthy habits.
Key Reminders:
- Follow your doctor’s guidance.
- Inject correctly and rotate sites.
- Stick to your schedule.
- Track your progress and check in regularly.
Need More Support?
We’re here to help! Leave a comment or question below, or talk to your healthcare provider if you’re unsure about your next step.
Citations:
Mehta A, Marso SP, Neeland IJ. Liraglutide for weight management: a critical review of the evidence. Obes Sci Pract. 2017 Mar;3(1):3-14. doi: 10.1002/osp4.84. Epub 2016 Dec 19. PMID: 28392927; PMCID: PMC5358074. <https://pmc.ncbi.nlm.nih.gov/articles/PMC5358074/>
Authors: John P.H. Wilding, D.M., Rachel L. Batterham, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. Published February 10, 2021. N Engl J Med 2021;384:989-1002. DOI: 10.1056/NEJMoa2032183 VOL. 384 NO. 11 <https://www.nejm.org/doi/full/10.1056/NEJMoa2032183>
Aroda VR, Blonde L, Pratley RE. A new era for oral peptides: SNAC and the development of oral semaglutide for the treatment of type 2 diabetes. Rev Endocr Metab Disord. 2022 Oct;23(5):979-994. doi: 10.1007/s11154-022-09735-8. Epub 2022 Jul 15. PMID: 35838946; PMCID: PMC9515042. https://pmc.ncbi.nlm.nih.gov/articles/PMC9515042/
Yang XD, Yang YY. Clinical Pharmacokinetics of Semaglutide: A Systematic Review. Drug Des Devel Ther. 2024 Jun 25;18:2555-2570. doi: 10.2147/DDDT.S470826. PMID: 38952487; PMCID: PMC11215664. https://pmc.ncbi.nlm.nih.gov/articles/PMC11215664/
Wegovy Package Insert: (Prescribing information)
https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b
Mounjaro Package Insert: (Prescribing information)
https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=d2d7da5d-ad07-4228-955f-cf7e355c8cc0
The Joint Commission. (2025). Vials – Managing Multi-dose Vials of Injectable Medication. https://www.jointcommission.org/standards/standard-faqs/home-care/medication-management-mm/000001529/
Centers for Disease Control and Prevention. (2025, April 9). Injection Practices and Your Health. CDC. https://www.cdc.gov/injection-safety/about/index.html
Rodriguez PJ, Goodwin Cartwright BM, Gratzl S, et al. Semaglutide vs Tirzepatide for Weight Loss in Adults With Overweight or Obesity. JAMA Intern Med. 2024;184(9):1056–1064. doi:10.1001/jamainternmed.2024.2525 https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2821080