Common side effects of flu shots are soreness, redness and swelling at the shot site, according to MedicineNet. Fevers and aches are possible but less common. These side effects typically last no longer than two days.
Although rare, patients can have an allergic reaction to flu shots. Symptoms of an allergic reaction include breathing difficulties, wheezing, hives, pale skin, dizziness and a pounding heartbeat. Those allergic to eggs are more likely to experience an allergic reaction to flu shots since the viruses used in making the flu shots are grown in chicken eggs, states MedicineNet. Patients with eggs allergies should talk with their doctors about their options.