Freeper lightman recommends taking tylenol with the second shot, to reduce side effects.
Most people who experience side effects from the shots (hangover-like or flu-like symptoms), experience them only after the second shot (shows its working - the immune system mobilizes strongly).
Generally, a few hours to a day after the second shot, it is best to plan on just relaxing, especially if you are older. A lot of folks, including folks in their eighties, don’t really experience much from the second shot, but it is still probably wise to not schedule any commitments.
Best to figure that from about the 9th hour after the injection until about the 36th you might not be good for very much.
Tylenol will mitigate but not eliminate.
About 10 days after my first injection I had gout like symptoms and pain in joints where I’d never had pain before. Today was day 13 after the second and so far, so good on that front.