Objective To determine the relationship between health misinformation on social media and adverse health outcomes.

Methods We analyzed 16,729 calls to the Regional Center for Poison Control and Prevention serving Massachusetts and Rhode Island (MARI PCC) and 25,231 tweets discussing treating COVID-19 with house cleaners.

Results Half of the spikes in calls to MARI PCC about exposures to cleaners were preceded 2–3 days earlier by tweets advocating ingesting or insufflating bleach to cure COVID-19. The relationship was only statistically significant for tweets in the Greater Boston Area and calls to MARI PCC. [Results of network analysis].

Conclusions Health misinformation on social media had a spatiotemporally specific relationship with increased calls to Poison Control and referrals to hospitals for cleaner ingestions. The spatiotemporal specificity of our results strengthens our conviction that the increased calls were driven in part by health misinformation on social media.

Public Health Implications Health misinformation can directly lead to secondary harm. Thematically targeted messages at specific loci in the social network may stem this harm.

The authors have declared no competing interest.

No specific funding was received for this project.

All relevant ethical guidelines have been followed; any necessary IRB and/or ethics committee approvals have been obtained and details of the IRB/oversight body are included in the manuscript.

Yes

All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

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I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.

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All supporting code is available upon request. Deidentified versions of underlying data may be available on an individual basis.