Sweats from flu shot; Chills; Fever; Pain 2 out of 10 at is left lower abdomen site; Red dots, dryness underneath subcut Remodulin site dressing; Initial information was received on 25-Nov-2020 regarding an unsolicited valid serious case from a consumer/non-health care professional.  This case involves a 53 years old male patient (71.5 kg) who had sweats from flu shot (hyperhidrosis), chills, fever (pyrexia), pain 2 out of 10 at left lower abdomen site (infusion site pain) and red dots, dryness underneath subcutaneous remodulin site dressing (dermatitis contact), while he received INFLUENZA VACCINE and while being treated with TREPROSTINIL SODIUM [REMODULIN] and SELEXIPAG [UPTRAVI].  Medical history, medical treatment(s), past vaccination(s) and family history were not provided.  Concomitant medications included MACITENTAN (OPSUMIT); APIXABAN (ELIQUIS) and SILDENAFIL CITRATE (REVATIO).  On 16-Nov-2020, the patient started taking 0.0155 mcg/kg REMODULIN (TREPROSTINIL SODIUM) (lot - 936696, 31-May-2021) subcutaneously for Pulmonary arterial hypertension.  On an unknown date, the patient started therapy with UPTRAVI (SELEXIPAG) (dosing regimen not reported) for an unknown indication.  On an unknown date, the patient received a dose of suspect INFLUENZA VACCINE produced by unknown manufacturer lot number not reported via unknown route in unknown administration site for prophylactic vaccination.  On an unknown date in Nov-2020, the patient developed serious sweats from flu shot (hyperhidrosis), chills, fever (pyrexia), pain 2 out of 10 at is left lower abdomen site (infusion site pain) and red dots, dryness underneath subcutaneous Remodulin site dressing (dermatitis contact) (unknown latency) following administration of INFLUENZA VACCINE, TREPROSTINIL SODIUM and SELEXIPAG.  It was reported that the patient discontinued Uptravi while in the hospital and transitioned to Remodulin.  It was reported that the patient was admitted to the hospital for starting Remodulin and was discharged on 17-Nov-2020.  Action taken with Remodulin, INFLUENZA and Uptravi was not reported for the events of infusion site pain and dermatitis. Action taken with Remodulin was not applicable for the events of chills, pyrexia, and hyperhidrosis. Action taken with Flu and Uptravi was not reported for the events of chills, pyrexia and hyperhidrosis.   It was not reported if the patient received a corrective treatment.  At the time of reporting, the outcome of chills, pyrexia and hyperhidrosis was considered as recovering while the outcome of events infusion site pain and dermatitis contact was unknown.  The reporter assessed the causal relationship between the Remodulin and the events of chills, pyrexia and hyperhidrosis as not related. The reporter did not provide causality for the events of infusion site pain and dermatitis contact.  Case Comment/Senders Comment: The company has assessed the serious adverse event of chills, pyrexia, and hyperhidrosis as not related to treprostinil and likely related to flu shot.  Information on lot number was requested for this case.; Sender's Comments: This case concerns 53 years old male patient who had chills, pyrexia, hyperhidrosis, infusion site pain and dermatitis contact after administration of INFLUENZA VACCINE and while being treated with REMODULIN and UPTRAVI. The time to onset is compatible. Additional information regarding medical history, concurrent condition and lab data excluding other predisposing etiologies would be needed for complete assessment of the case. Based upon the reported information, the role of suspect products cannot be assessed.