COVID-19 vaccines can cause side effects, most of which are mild and temporary. Common side effects include:

1. **Pain at the injection site**

2. **Fatigue**

3. **Headache**

4. **Muscle pain**

5. **Chills**

6. **Fever**

7. **Nausea**

Less common side effects can include:

1. **Swelling or redness at the injection site**

2. **Enlarged lymph nodes**

3. **Joint pain**

Rare but serious side effects, such as severe allergic reactions (anaphylaxis), myocarditis, and blood clotting disorders, have also been reported but are exceedingly rare.

Most side effects occur within a few days of vaccination and resolve on their own. It’s always best to consult with a healthcare provider if you have concerns about vaccine side effects.