Visine eyedrops provide relief from red eyes. The active ingredient in Visine acts to constrict the blood vessels in the eye so that the eye appears less red. The most common side effect of Visine is burning upon instillation. Long-term use of Visine can actually cause the eyes to appear more red. Visine can cause severe medical problems if ingested.
How Visine Works
Tetrahydrozoline hydrochloride is the active ingredient in original formula Visine drops. When irritation causes the eyes to be red, the active ingredient in Visine works to constrict the blood vessels, making the eye appear white again.
Immediate Side Effects
Visine often causes stinging of the eye upon instillation. It also reduces bloodflow and oxygenation to the surface of the eye, and therefore should not be used with contact lenses, which tend to reduce oxygen flow to the eye on their own. Some Visine users experience a rapid heartbeat after instilling Visine original formula.
Long-term Side Effects
Visine original formula is not indicated for long-term use of more than several days in a row. This is because long-term use will result in the blood vessels in the eye growing accustomed to the Visine, and a "rebound redness" will occur, making the eye appear significantly more red unless Visine is instilled. Thus, long-term use of Visine original formula will actually make your eyes appear redder. Long-term use of Visine original formula can also damage the ocular surface.
Ingestion of Visine
A common myth about Visine is that it causes diarrhea if ingested. This is false. Instead, ingesting Visine can cause a multitude of serious medical problems, including vomiting, serious reductions in blood pressure and heart rate, and coma.
Red eyes can be a sign of a greater problem inside the eye. If you have a persistent red eye, see your eye doctor.