Semaglutide & Tirzepatide Side Effects: Complete Guide to Contraindications

Understanding GLP-1 Medication Side Effects

GLP-1 receptor agonists like semaglutide and tirzepatide are among the most effective weight loss medications available today. Like all prescription medications, they carry potential side effects ranging from mild and manageable to rare but serious. Understanding these effects before starting treatment helps you make informed decisions and recognize when to contact your provider.

Common Side Effects of Semaglutide

The most frequently reported side effects of semaglutide are gastrointestinal in nature, particularly during dose escalation phases. These typically improve as your body adjusts to the medication.

• Nausea — affects up to 44% of patients, most common in the first 4–8 weeks
• Vomiting — reported in about 24% of patients during initial titration
• Diarrhea — occurs in approximately 30% of users
• Constipation — affects up to 24% of patients
• Abdominal pain or discomfort
• Decreased appetite (desired effect, but can be excessive in some)
• Fatigue, especially in the first few weeks
• Headache during dose increases
• Injection site reactions (redness, swelling, itching)

Common Side Effects of Tirzepatide

Tirzepatide's dual GLP-1 and GIP receptor activity produces a similar side effect profile to semaglutide, though some studies suggest slightly higher rates of GI symptoms due to its dual mechanism. In clinical trials (SURMOUNT program), the following were most commonly reported:

• Nausea — up to 45% of participants at the 15mg dose
• Diarrhea — approximately 30% across all doses
• Vomiting — reported in 20–25% during titration
• Constipation — affects roughly 17% of patients
• Decreased appetite and early satiety
• Dyspepsia (indigestion)
• Abdominal pain
• Hair thinning (telogen effluvium) — often temporary
• Injection site reactions

Serious Warnings and Black Box Alerts

Both semaglutide and tirzepatide carry a black box warning regarding thyroid C-cell tumors. In rodent studies, GLP-1 receptor agonists caused thyroid C-cell tumors at clinically relevant exposures. It is unknown whether these drugs cause thyroid C-cell tumors in humans. These medications are contraindicated in patients with a personal or family history of medullary thyroid carcinoma (MTC) or in patients with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2).

Other serious but rare risks include: acute pancreatitis (discontinue immediately if suspected), acute kidney injury (often secondary to dehydration from GI effects), serious hypersensitivity reactions, diabetic retinopathy complications (primarily in type 2 diabetes patients), and suicidal ideation (under review; contact provider if you experience mood changes).

Contraindications: Who Should Not Take These Medications

Certain individuals should not use GLP-1 receptor agonists. Your Cora physician reviews your health history specifically to screen for these contraindications during the assessment process.

• Personal or family history of medullary thyroid carcinoma (MTC)
• Multiple Endocrine Neoplasia syndrome type 2 (MEN 2)
• Known hypersensitivity to semaglutide or tirzepatide or any excipients
• Pregnancy or active breastfeeding (discontinue at least 2 months before attempting conception)
• Severe gastrointestinal disease (e.g., gastroparesis)
• History of pancreatitis (use with caution or avoid)
• Severe renal impairment (eGFR < 15 mL/min)
• Concurrent use of other GLP-1 receptor agonists

Practical Tips for Managing Side Effects

Most GI side effects are manageable with lifestyle adjustments. Clinical experience suggests the following strategies significantly reduce discomfort:

• Eat smaller, more frequent meals — avoid large portions that overwhelm your slowed gastric emptying
• Stay well-hydrated — sip water throughout the day, especially if experiencing vomiting or diarrhea
• Avoid high-fat, greasy, or spicy foods in the first weeks of treatment
• Inject on a consistent day and time each week
• Ask your provider about anti-nausea options (e.g., ginger supplements, prescription ondansetron) if nausea is severe
• Do not rush through dose escalation — slower titration dramatically reduces side effects
• Avoid lying down immediately after eating

When to Contact Your Provider Immediately

While most side effects are mild, certain symptoms require prompt medical attention. Contact your Cora provider or seek emergency care if you experience:

• Severe abdominal pain that radiates to the back (possible pancreatitis)
• Persistent vomiting that prevents you from keeping down fluids
• Signs of allergic reaction: rash, swelling of the face or throat, difficulty breathing
• Vision changes
• Signs of dehydration: dizziness, dark urine, rapid heartbeat
• Unusual changes in mood or thoughts of self-harm
• A lump or swelling in the neck, hoarseness, or trouble swallowing