GLP-1 Agonists (Semaglutide, Tirzepatide, Liraglutide)
Weekly injections originally for diabetes — now major treatments for obesity, MASLD/MASH, and weight-related conditions. Side effects include nausea, especially when starting.
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
Drug class
GLP-1 receptor agonists (and dual GIP/GLP-1 agonists)
Examples
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.
What it treats
- 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)
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.
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
Serious side effects — call your doctor
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 and how to stop
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 & 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 the Saudi context
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
Save this list or print it before your appointment — doctors appreciate prepared patients.
- 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?
Medically reviewed by: SGA Patient Education Panel · Last reviewed 24/04/2026