 The symptoms of H1N1 flu are similar to those of other <unk> , and may include fever , cough ( typically a " dry cough " ) , headache , muscle or joint pain , sore throat , chills , fatigue , and runny nose . Diarrhea , vomiting , and neurological problems have also been reported in some cases . People at higher risk of serious complications include those aged over 65 , children younger than 5 , children with neurodevelopmental conditions , pregnant women ( especially during the third trimester ) , and those of any age with underlying medical conditions , such as asthma , diabetes , obesity , heart disease , or a weakened immune system ( e.g. , taking immunosuppressive medications or infected with HIV ) . More than 70 % of hospitalizations in the U.S. have been people with such underlying conditions , according to the CDC . 
