Don't panic. Most side effects that occur are self-limiting, meaning they go away on their own.
If something minor (ex: headache, mild nausea or GI upset, etc), treat it with over-the-counter medication or manage the symptoms as if you would normally
If something more serious (ex: migraine or diarrhea for > 1 day, rash, etc), please reach out to your provider to discuss
If something major (ex: worst headache of your life, chest pain, difficulty breathing, allergic reaction, etc), please go to the ED immediately and reach out to your provider afterwards