What happens if you put a few drops of visine under your tongue?

Putting Visine, which contains the active ingredient tetrahydrozoline, under your tongue is not recommended. This eye drop is designed for topical use in the eyes and can cause irritation or adverse reactions if absorbed sublingually. Tetrahydrozoline is a vasoconstrictor, and using it improperly could lead to systemic effects, such as increased heart rate or elevated blood pressure. Always use medications as directed and consult a healthcare professional for appropriate use.