Starting Wegovy is a big step for many people trying to manage weight. The first dose marks the beginning of how your body responds to semaglutide. Most people want to know exactly what will happen in the hours and days after that initial injection.
The starting dose is very low—only 0.25 mg—to help your body adjust slowly. Changes usually begin within the first few days, but they can feel subtle at first. Both positive effects and side effects tend to appear early.
This article explains what typically happens after the first injection. It covers physical sensations, appetite changes, side effects, and practical tips. The goal is to help you feel more prepared and less surprised.
How the First Dose of Wegovy Works
Wegovy is a weekly injection that mimics the GLP-1 hormone your gut naturally releases after eating. After the first dose, small amounts of semaglutide enter your bloodstream and start reaching receptors in the brain and digestive system. This process begins within hours.
The low starting dose is intentionally gentle. It allows your body to get used to the medication while minimizing strong side effects. Full effects take several weeks to build, but some changes can start sooner.
The drug works in three main ways: it signals fullness to the brain, slows down how quickly food leaves the stomach, and helps regulate blood sugar. Even at 0.25 mg, these actions begin, though they are mild compared to higher doses.
Most people notice that food no longer feels as urgent or exciting. This subtle shift is often the first sign that the medication is doing something.
Timeline: What Happens in the First Week
Hours 1–12 After Injection
Many people feel completely normal right after the shot. The medication absorbs slowly because it is given under the skin. Some report a slight headache or mild tiredness within the first 12 hours.
Injection site reactions—such as redness, itching, or a small bump—are possible but usually minor. These typically fade within a day or two. No dramatic changes happen this quickly for most users.
Sleep may feel normal or slightly disrupted if anxiety about starting the medication is present. Staying hydrated and resting helps smooth this initial period.
Days 1–3: Early Signs Appear
This is when most people notice the first real changes. Appetite often begins to decrease noticeably. Many describe feeling satisfied after eating much smaller amounts than usual.
Some experience mild nausea, especially when eating larger or richer meals. The stomach feels full faster and stays full longer. Cravings for sweets or snacks tend to drop.
Energy levels can vary. Some feel more tired than normal, while others report no change in energy. Headaches are reported by a minority of users during these early days.
Days 4–7: Effects Become More Noticeable
By the end of the first week, appetite suppression usually feels more consistent. People often eat fewer calories without deliberately trying to cut back. Food thoughts become less frequent.
Nausea may peak around days 3–5 for those who experience it, then start to ease. Many find that eating slowly and choosing lighter meals helps a lot. Some notice improved portion awareness.
Weight may drop 1–4 pounds by the end of week one, though much of this is water weight. Clothes might feel slightly looser. Motivation often increases when early changes become clear.
Common Side Effects After the First Dose
The most frequent side effect is nausea. It affects 20–40% of people after the first injection. Nausea is usually mild to moderate and improves within a few days to a week.
Digestive changes are very common. These include:
- Mild constipation
- Loose stools or diarrhea
- Bloating or a feeling of fullness
- Burping more than usual
Headache and fatigue occur in some users. These symptoms are generally short-lived. Drinking plenty of water and resting when needed helps most people.
Injection site reactions are usually minor. Redness, itching, or a small raised area can appear. Rotating injection sites (abdomen, thigh, upper arm) reduces irritation over time.
Tips to Manage the First Week Smoothly
Here are practical steps that help most people handle the first dose better:
- Eat small, frequent meals instead of large ones
- Choose bland, low-fat foods when nausea is present
- Avoid lying down right after eating
- Drink water steadily throughout the day
- Keep ginger tea, peppermint, or crackers on hand
- Rest if fatigue appears—do not push through heavy activity
- Track symptoms and food intake in a simple notebook or app
These adjustments make the adjustment period much easier. Most side effects lessen significantly by the second or third week.
Weight and Appetite Changes in Week One
Appetite reduction is usually the most noticeable effect after the first dose. Many people report that hunger feels different—less intense and shorter-lived. Emotional eating triggers lose some power.
Weight loss in the first week varies widely. Average reported loss ranges from 0.5 to 4 pounds. Heavier individuals tend to see slightly larger numbers early on.
It is important not to focus too much on the scale in week one. Water shifts, digestion changes, and reduced food volume all influence early readings. The real progress becomes clearer over weeks two to four.
Comparison: First Dose vs. Higher Doses
This table compares what people typically experience after the first dose (0.25 mg) versus later maintenance doses (1.7–2.4 mg).
| Aspect | After First Dose (0.25 mg) | At Maintenance Dose (1.7–2.4 mg) |
|---|---|---|
| Appetite Suppression | Mild to moderate | Strong and consistent |
| Nausea / GI Side Effects | Most common and often peak here | Much lower once body adjusts |
| Weight Loss in Period | 0.5–4 lbs (mostly water) | 1–3 lbs per week (mostly fat) |
The first dose is intentionally gentle to help you build tolerance. Stronger effects come later, but so do better results.
What to Watch For: When to Contact Your Doctor
Most early side effects are expected and manageable. However, certain symptoms deserve prompt attention. Severe vomiting that prevents keeping fluids down needs medical evaluation.
Persistent abdominal pain—especially if sharp or spreading to the back—should be checked quickly. This can be a rare sign of pancreatitis, though it is uncommon.
Signs of dehydration (dry mouth, dizziness, dark urine) should be addressed. Increasing fluid intake usually helps, but medical advice is wise if symptoms continue.
Any new or worsening symptoms that worry you deserve a call. It is always better to ask than to wonder.
Realistic Expectations for the First Month
The first dose is just the starting point. The medication builds up in your system over weeks. By the end of month one, most people notice clearer appetite control and steadier weight loss.
Many report losing 4–10 pounds in the first month. Side effects usually decrease significantly. Habits start to shift—eating becomes more intentional and less driven by cravings.
Progress feels gradual rather than dramatic. Patience during the early phase sets the stage for better long-term results. Consistency with injections and lifestyle changes matters most.
Preparing for Your Second Dose
Before your next injection, review how the first week went. Note any side effects and how you managed them. This information helps your doctor decide whether to stay at 0.25 mg for another month or move to 0.5 mg.
Continue the strategies that worked well—small meals, good hydration, light activity. Build on early wins rather than expecting overnight transformation.
Many people feel more confident after the first dose because they know what to expect. That confidence makes the second dose easier to handle.
Conclusion
The first dose of Wegovy usually brings mild appetite changes, possible nausea, and subtle weight shifts within the first week. Side effects are common but typically short-lived and manageable with simple adjustments. Understanding what to expect helps reduce worry and sets a realistic foundation for continued progress with the medication.
FAQ
How soon after the first dose do you feel effects?
Many people notice reduced appetite within 1–3 days. Nausea can start as early as the first day. Effects are usually mild at the 0.25 mg starting dose.
Is nausea after the first dose normal?
Yes, nausea is the most common side effect early on. It affects many users but often improves within a few days to a week. Eating small, bland meals helps reduce it.
How much weight can you lose after the first dose?
Most people lose 0.5–4 pounds in the first week. Much of this is water weight and reduced food volume. True fat loss becomes more noticeable later.
Should I eat less right after my first injection?
You do not need to force a strict diet. The medication naturally reduces appetite. Focus on smaller portions and lighter foods if nausea appears.
What should I do if nausea is very strong?
Eat very small amounts of bland food frequently. Try ginger tea, crackers, or toast. Contact your doctor if you cannot keep fluids down.
Will I feel tired after the first dose?
Some people feel more tired or fatigued for a few days. Others notice no change in energy. Resting and staying hydrated usually helps.
Can I exercise after my first Wegovy injection?
Light activity like walking is usually fine. Avoid intense workouts if you feel nauseous or tired. Listen to your body during the first week.
When do side effects usually improve?
Most side effects peak in the first 1–2 weeks and then gradually decrease. By the third or fourth week, many people feel much better.
Is the first dose the same for everyone?
Yes, everyone starts at 0.25 mg once weekly. This low dose helps your body adjust. Your doctor may keep you at this level longer if needed.
What happens if I miss my second dose?
Try to take it as soon as possible. If more than a few days late, talk to your doctor. Missing doses can slow progress and increase side effects when restarting.
Dr. Usman is a medical content reviewer with 12+ years of experience in healthcare research and patient education. He specializes in evidence-based health information, medications, and chronic health topics. His work is based on trusted medical sources and current clinical guidelines to ensure accuracy, transparency, and reliability. Content reviewed by Dr. Usman is for educational purposes and does not replace professional medical advice.