Once you have received the COVID-19 vaccine, the side effects are usually reasonably immediate. This rings true for both the initial vaccination and any booster vaccinations. It has been seen that most people who receive the vaccination will see side effects within the first 24 hours. The symptoms will typically only last a day or two after that, and some people will never notice any side effects.   If you want to minimize the side effects after a COVID-19 vaccination, you can:   - Take over-the-counter ibuprofen or acetaminophen if the doctor who provided the vaccination allows it. - Apply a cold compress or cool, wet washcloth to the injection area. - Walk and move your arm in an up and down motion, like a chicken, rather than sitting idly.   While the side effects are often only mild to moderate, some of the most common side effects include:   - Pain at the site of the injection - Fatigue - Swelling and/or redness at the site of the injection - Headache - Muscle pain - Joint pain - Chills - Fever - Vomiting or nausea - Swollen lymph nodes underneath the arm that received the COVID-19 injection.