GLP-1 Agonists (Semaglutide, Tirzepatide, Liraglutide)
Overview
Weekly injections originally for diabetes — now major treatments for obesity, MASLD/MASH, and weight-related conditions. Side effects include nausea, especially when starting.
What it is used for
Type 2 diabetes — first-line for many patients
Obesity and weight management (with BMI ≥30, or ≥27 with comorbidities)
MASLD/MASH — emerging major use
Cardiovascular disease prevention in diabetes (some agents)
Heart failure with preserved ejection fraction (semaglutide)
Sleep apnea (tirzepatide approved 2024)
Common side effects
Nausea (most common — usually settles after 4-6 weeks)
Vomiting
Diarrhea or constipation
Acid reflux
Decreased appetite (often desired but can be excessive)
Fatigue, mild headache
Injection site reactions
When to See a Doctor
Do not stop a prescribed medicine on your own. Speak to your doctor or pharmacist about side effects, interactions or any doubt, and seek urgent care for the serious warning signs above.
Drug class and examples
GLP-1 receptor agonists (and dual GIP/GLP-1 agonists)
GLP-1: semaglutide (Ozempic for diabetes, Wegovy for weight loss, Rybelsus oral form), liraglutide (Victoza, Saxenda), dulaglutide (Trulicity).
Dual GIP/GLP-1: tirzepatide (Mounjaro for diabetes, Zepbound for weight loss).
How it works
These drugs mimic GLP-1, a natural gut hormone. They: (1) increase insulin in response to food (improving diabetes), (2) slow stomach emptying (you feel full longer), (3) act on the brain to reduce appetite, and (4) modestly reduce liver fat. Tirzepatide adds GIP receptor activity for stronger weight loss.
How to take it
**Semaglutide (Ozempic/Wegovy)**: weekly subcutaneous injection (abdomen, thigh, or upper arm). Start at low dose, increase every 4 weeks (0.25 → 0.5 → 1 → 2 → 2.4 mg) to allow tolerance.
**Tirzepatide (Mounjaro/Zepbound)**: weekly subcutaneous injection. Start 2.5 mg, increase monthly to maintenance 5-15 mg.
**Liraglutide (Saxenda)**: DAILY subcutaneous injection.
**Oral semaglutide (Rybelsus)**: tablet with empty stomach, only water for 30 minutes after.
Rotate injection sites.
Serious side effects — act on these
• Severe persistent abdominal pain radiating to back — Possible pancreatitis — STOP medication and go to ED.
• Severe vomiting unable to keep fluids down — Risk of dehydration and gastroparesis — see doctor.
• Right upper abdominal pain with jaundice — Possible gallbladder problems (more common on rapid weight loss).
• Lump in neck, hoarseness, persistent cough — Rare risk of medullary thyroid cancer — get evaluated.
• Hypoglycemia symptoms in patients on insulin/sulfonylurea — Adjust other diabetes medications.
Interactions
GLP-1 drugs slow stomach emptying — can affect absorption of oral medications (especially those with narrow therapeutic window). Not many drug-drug interactions otherwise. Combine carefully with insulin/sulfonylureas (hypoglycemia risk).
Monitoring
Diabetes patients: HbA1c every 3 months. All patients: monitor weight, side effects, kidney function periodically. Pancreatic enzymes if pancreatitis suspected. Thyroid exam for any neck symptoms.
When to stop or review
STOP immediately for: severe pancreatitis, severe persistent vomiting, planned anesthesia (hold for 1 week before non-emergency surgery to reduce aspiration risk), pregnancy. For weight loss: stopping usually leads to weight regain — long-term continuation often needed for maintenance.
Pregnancy and breastfeeding
CONTRAINDICATED in pregnancy. Stop at least 2 months before planning pregnancy. If you become pregnant on the drug, stop and contact your doctor.
In Saudi Arabia
Highly used in Saudi Arabia for both diabetes and weight loss. Available at all pharmacies; insurance coverage variable for non-diabetes use. Several Saudi obesity clinics integrate GLP-1 treatment with bariatric pathways.
Questions to ask your doctor
• Am I a candidate for GLP-1 therapy?
• How fast will I lose weight?
• How long will I need to stay on it?
• What's the difference between Ozempic and Wegovy and Mounjaro?
Source and review
This guide comes from the Saudi Gastroenterology Association (SGA) patient library, prepared by the SGA Patient Education Panel. Last reviewed: 2026-04-24. It is for education and does not replace your doctor's advice.
Frequently Asked Questions
What is GLP-1 Agonists (Semaglutide, Tirzepatide, Liraglutide) used for?
How does GLP-1 Agonists (Semaglutide, Tirzepatide, Liraglutide) work?
What are the side effects of GLP-1 Agonists (Semaglutide, Tirzepatide, Liraglutide)?
When should I call my doctor about GLP-1 Agonists (Semaglutide, Tirzepatide, Liraglutide)?
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