Short answer: acid can irritate the esophagus and worsen reflux in people prone to it — a genuine, mechanism-based consideration alongside the more commonly discussed enamel and potassium cautions.
Why this caution deserves its own mention
Regular exposure to an acidic substance can irritate the throat, distinct from the enamel-erosion concern — anyone with existing reflux should weigh this before starting.
What mild digestive upset looks like when starting
Most people tolerate it, but a minority notice mild digestive upset, nausea or heartburn in the first week — a genuine, disclosed possibility rather than a claim of zero side effects.
Why "no side effects reported" would be an unhelpful claim
You'll read elsewhere that no side effects have been reported with similar products — that's not a useful statement, because apple cider vinegar has well-documented cautions and they apply here regardless of anecdotal review patterns.
Read the full safety page before starting
Every documented caution, stated plainly.
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