Some eye drops contain only sterile saline solution, which is not
harmful if ingested. However, other eye drops can be hazardous if they
are consumed. Ingesting eye drops that contain tetrahydrozoline can
potentially be fatal, particularly to small children.
"The active ingredient in Visine eye drops is Tetrahydrozoline HCl
0.05%. Swallowing this substance can result in a number of nasty
effects, including:
Lowering body temperature to dangerous levels
Making breathing difficult, or even halting it entirely
Blurring vision
Causing nausea and vomiting
Elevating and then dropping blood pressure
Causing seizures or tremors
Sending the ingester into a coma
Pfizer's cautions to users of Visine include, 'If swallowed, get
medical help or contact a Poison Control Center right away.' In view
of the above list, that advice should not be taken lightly."