VACCINE INDUCED PHANTOSMIA/OLFACTORY HALLUCINATIONS; CHRONIC SINUSITIS; This spontaneous report was received from other health professional via literature. This report concerned a 39 year old male of unspecified race and ethnicity. The objective of the authors was to present a patient who has developed olfactory hallucinations following the administration of the J and J vaccine. The patient's height, and weight were not reported. The patient's pre-existing medical conditions included: The patient did not sustain any head injuries or exposure to toxic odors before the onset of symptoms. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin, batch number and expiry date were not reported) dose, start therapy date were not reported, 1 in total administered for covid-19 prophylaxis. Age at time of vaccination 4 decade old. The batch number was not reported and has been requested. No concomitant medications were reported.  On an unspecified date, 3 weeks after vaccination, the patient experienced vaccine induced phantosmia/olfactory hallucinations. It was reported that with a history of tension-type headaches, the patient was presented to the neurology clinic with concern of a burning smell sensation in the absence of an identifiable source. The patient first noticed this symptom (burning smell sensation) approximately 3 weeks after he received the J and J COVID-19 vaccine about 4 months prior to visiting clinic. At the symptom's first occurrence, on an unspecified date, the patient underwent a nasal swab antigen COVID-19 test which was negative. Initially, symptoms would occur daily lasting about 1 hour. Thereafter, they started to decrease in duration, frequency, and intensity, and about 11 months post vaccination, milder episodes were occurring 1 to 2 times weekly. These episodes lasted nearly 2 years (21 months post vaccination). They happened randomly during the day and were not associated with any other symptoms. There were no headaches, loss of consciousness, abnormal movements, nausea, vomiting, photophobia or phonophobia, or alteration of consciousness, such as confusion or drowsiness during or after the events. At the time of his presentation to the clinic, patient's general and neurological examinations were unremarkable. Brain magnetic resonance imaging (MRI) showed chronic sinusitis but no other abnormalities. However, the phantosmia persisted after the sinusitis had been treated with a course of doxycycline (treatment medications-dates unspecified). An electroencephalogram (EEG) was obtained and was unremarkable. However, the EEG did not capture the episodes of phantosmia. It did not show abnormalities in the temporal region. Together the clinical and paraclinical evidence along with the timing of symptom onset in relation to vaccination pointed toward a new onset of phantosmia as an adverse event of the J and J vaccination. In the evaluation of this patient, the author reported that although the timing between symptom onset and vaccination was indicative of a possible link between the 2, other etiologies of phantosmia were ruled out. However, given the absence of other symptoms suggestive of epilepsy and the duration of the episodes (approximately 1 hour), the clinical suspicion was low. This was reinforced by the EEG that showed no abnormalities in the temporal region. However, no episodes of phantosmia occurred during the EEG recording, the correlates of which were the standard to rule out a diagnosis of epilepsy. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from vaccine induced phantosmia/olfactory hallucinations, and the outcome of chronic sinusitis was not reported. The authors concluded that, this case demonstrates phantosmia reported after the use of the J and J COVID-19 vaccine and aligns with the literature that reports one case of phantosmia and two cases of hyposmia following the Pfizer-BioNTech COVID-19 mRNA vaccine. This information would help health care professionals understand the possible adverse effects of COVID-19 vaccination and be better equipped to counsel patients about the benign but potentially long lasting adverse effects of the J and J COVID-19 vaccine. This report was serious (Other Medically Important Condition).; Sender's Comments: V0: 20230969695-vaccine induced phantosmia/olfactory hallucinations, . 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. Therefore, the WHO Causality is considered indeterminate. The company causality is considered unassessable.