Possible side effects include:
- Fever (low grade)
- Soreness, redness, or swelling where the shot was given
The intradermal flu shot may cause other additional mild side effects including toughness and itching where the shot was given. If these problems occur, they begin soon after the shot and usually last one to two days. Life-threatening allergic reactions are very rare. If any unusual condition occurs following vaccination, seek medical attention right away.