ADDISON'S DISEASE; ADRENOCORTICAL INSUFFICIENCY ACUTE; DEPRESSED LEVEL OF CONSCIOUSNESS; SYNCOPE; BALANCE DISORDER; COMMUNICATION DISORDER; CONDITION AGGRAVATED; CONFUSIONAL STATE; GAIT INABILITY; HYPERHIDROSIS; PAIN; PHOTOPSIA; TREMOR; PAIN IN EXTREMITY; HEADACHE; FATIGUE; This spontaneous report received from a health care via the VAERS (Vaccine Adverse Event Reporting System) (VAERS ID: 1430251) concerned a 34-year-old white male of unspecified ethnic origin. The patient's height, and weight were not reported. The patient's concurrent conditions included Hashimoto's thyroiditis, Addison's disease, lupus, anaphylaxis, asthma, hay fever/allergies, food sensitivities, penicillin allergy, keflex allergy, clindamycin allergy, sulfa antibiotics/Bactrim allergy, oral allergy syndrome, preservatives allergies, environmental allergies, latex allergy, sensitivities to nickel, and sensitivities to other metals, and other pre-existing medical conditions included allergies to vinyl with extended exposure and nitrile with extended exposure. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: 59676058015, expiry: Unknown) dose was not reported, 1 total, administered at left arm on 28-Mar-2021 for prophylactic vaccination. Concomitant medications included budesonide, colecalciferol, fludrocortisone 0.05 mg, hydrocortisone 25 mg, levothyroxine sodium 112mcg and salbutamol. On 29-Mar-2021, the patient experienced tremors, sweating (hyperhidrosis), severe headache, vision flashes (photopsia), pain in arm (pain in extremity), fatigue, confusion, reduced consciousness (depressed level of consciousness), fainting (syncope), loss of balance (balance disorder), unable to ambulate (gait inability) or communicate (communication disorder), adrenal crisis (adrenocortical insufficiency acute), which started in morning and was  treated at home with oral steroids for Addison's disease. The doses were doubled for the next few days, pain and headache lasted more than other symptoms. Laboratory data was not required. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from addison's disease, adrenocortical insufficiency acute, depressed level of consciousness, syncope, balance disorder, communication disorder, condition aggravated, confusional state, gait inability, hyperhidrosis, pain, photopsia, tremor, pain in extremity, headache, and fatigue. This report was serious (Life Threatening).  Additional information was received on 07-SEP-2021. The following information was updated and incorporated into the case: Sender's Comments: V1: This version is created to update the information regarding Patient demographics and outcome. This does not change the causality of the previously reported events.: 20210721802-JANSSEN COVID-19 VACCINE Ad26.COV2.S- Addison's disease, Adrenocortical insufficiency acute, Depressed level of consciousness, Syncope, Balance disorder, Communication disorder, Condition aggravated, Confusional state, Gait inability, Hyperhidrosis, Pain, Tremor, Pain in extremity, Headache, and Fatigue. This event(s) is considered not related. The event(s) has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There are other factors more likely to be associated with the event(s) than the drug. Specifically: MEDICAL HISTORY, UNDERLYING DISEASE. 20210721802-JANSSEN COVID-19 VACCINE Ad26.COV2.S- Photopsia. This event is considered unassessable. The event has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There is no information on any other factors potentially associated with the event.