Side Effects

Week 1 on GLP-1: What to Expect (Side Effects & Tips)

You've just started your GLP-1 medication, and you're probably feeling a mix of excitement and nervousness. Whether you've been prescribed semaglutide or tirzepatide, that first week can feel like unfamiliar territory. The good news? Most people tolerate these medications well, especially when they know what to expect. Let's walk through what your first seven days might look like, so you can feel prepared and confident as you begin this journey.

What Happens in Your Body During Week 1

GLP-1 medications work by mimicking a natural hormone that regulates blood sugar and appetite. When you take your first dose, the medication begins slowing down how quickly food leaves your stomach and sending signals to your brain that help reduce hunger.

This is why many people notice changes in their appetite almost immediately. Some describe feeling full after just a few bites, while others simply notice they're not thinking about food as much throughout the day.

Your body is adjusting to these new signals, which is why the first week involves the lowest possible dose. This gradual start helps minimize side effects while your system adapts.

Common Side Effects in Week 1

Nausea

Nausea is the most commonly reported side effect during the first week, affecting about 15-20% of people starting GLP-1 therapy. For most, it's mild and comes in waves rather than being constant.

The nausea typically feels worse on an empty stomach or right after eating a large meal. It usually peaks within the first 2-3 days after your injection and gradually improves as the week goes on.

Reduced Appetite

While this is technically the intended effect, the sudden change can feel strange. You might find yourself forgetting to eat or feeling full after just a few bites of a meal.

Some people worry they're not eating enough. Remember that reduced appetite is how the medication works, but you still need adequate nutrition. Focus on nutrient-dense foods even if portions are smaller.

Digestive Changes

Because GLP-1 medications slow digestion, you may experience:

These effects are usually temporary and improve as your body adjusts to the medication.

Fatigue

Some people report feeling more tired than usual during the first week. This can happen because you're eating less than your body is accustomed to, or simply as part of the adjustment period.

If you're feeling fatigued, make sure you're staying hydrated and getting adequate protein and essential nutrients even with smaller portions.

Less Common Side Effects

A smaller percentage of people may experience headaches, dizziness, or heartburn during week one. These typically resolve on their own but are worth mentioning to your healthcare provider if they persist.

Gender Differences to Know

While GLP-1 medications work similarly across genders, some differences have been observed in clinical practice.

Women may be slightly more likely to experience nausea, particularly during the first few weeks of treatment. This may be related to hormonal factors or differences in how medications are metabolized.

Men tend to report less nausea overall but may be more likely to notice fatigue initially, possibly because they typically have higher baseline caloric needs.

These are general trends, not rules. Your individual experience is what matters most, regardless of gender.

What You Probably Won't Experience in Week 1

It's helpful to know what typically doesn't happen during your first week, so you don't have unrealistic expectations.

Significant weight loss is unlikely in just seven days. While some people notice the scale moving slightly, others see no change at all. Week 1 is about adjustment, not dramatic results.

Severe side effects are rare at the starting dose. The low initial dose is specifically designed to help your body adapt gradually.

Complete elimination of hunger isn't typical right away. The appetite suppression builds over time as you increase to therapeutic doses.

Tips for Managing Week 1

Eat Smaller, More Frequent Meals

Instead of three large meals, try eating smaller portions throughout the day. This can help prevent nausea and ensure you're getting adequate nutrition.

Stay Hydrated

Drink water consistently throughout the day. Dehydration can worsen nausea and fatigue. Aim for at least 64 ounces daily.

Choose Bland, Easy-to-Digest Foods

During week one, opt for foods that are gentle on your stomach. Think lean proteins, cooked vegetables, whole grains, and fruits. Save rich, fatty, or spicy foods for later when your body has adjusted.

Time Your Injection Strategically

Many people find that injecting in the evening helps them sleep through any initial side effects. Others prefer morning injections. There's no wrong answer—find what works for your schedule and how your body responds.

Move Gently

Light movement like walking can help with digestion and reduce nausea. Avoid intense workouts during the first few days if you're not feeling your best.

Keep a Simple Journal

Jot down how you're feeling, what you're eating, and any side effects. This information will be valuable for your healthcare provider and can help you identify patterns.

When to Contact Your Healthcare Provider

While most first-week experiences are normal and expected, reach out to your provider if you notice:

Your healthcare team is there to support you. It's always better to ask questions than to worry in silence.

Looking Ahead Beyond Week 1

Remember that week one is just the beginning. Most side effects improve significantly by weeks 2-3 as your body adapts. The starting dose is intentionally low, and your provider will gradually increase it based on how you're tolerating the medication and responding to treatment.

Give yourself grace during this adjustment period. Every person's experience is unique, and there's no "perfect" way to feel during your first week.

From the Ozari Care Team

The most important thing you can do during week one is stay in communication with your healthcare provider and listen to your body. If nausea occurs, try ginger tea or small sips of cold water, and remember that eating smaller portions of protein-rich foods often helps more than skipping meals entirely. Most patients find that side effects are mildest when they stay well-hydrated and avoid large, heavy meals during the first few days after their injection.

At Ozari Health, we offer compounded Semaglutide and Tirzepatide as low as $99/month, prescribed by licensed physicians and shipped to your door. Learn more at ozarihealth.com.

Medically Reviewed — Ozari Clinical Content Team (OCCT). Health writers and wellness professionals specializing in GLP-1 therapy, metabolic health, and weight loss medicine. Content reviewed in accordance with Ozari's Editorial Standards. Last reviewed: April 25, 2026.

This content is for informational purposes only and does not constitute medical advice. Always consult a licensed healthcare provider before starting any medication.

Last reviewed: April 25, 2026