Why does Naphazoline, Methapyrilene, and Vitamin B12 eye drops cause a stinging sensation in the eyes?

Burning sensation in the eyes after using naphazoline, chlorpheniramine and vitamin B12 eye drops may be due to normal physiological phenomena or pathological factors.

I. Physiological Phenomena

1. Irritation: When applying naphazoline, chlorpheniramine and vitamin B12 eye drops, the solution is instilled onto the cornea, which contains a rich network of nerve endings. This may trigger an irritative response in the cornea, manifesting as a burning sensation. This is generally considered a normal physiological reaction and typically resolves shortly afterward.

2. Cold medication: If the eye drops have been stored at a low temperature, the cool liquid may cause corneal intolerance upon instillation, resulting in a burning sensation.

II. Pathological Conditions

1. Allergic reaction: After using naphazoline, chlorpheniramine and vitamin B12 eye drops, some patients may experience allergy, which can also present as a burning sensation that lasts longer. It may be accompanied by other symptoms such as itching and redness of the eyes. In such cases, discontinue the medication promptly and initiate anti-allergic treatment.

2. Conjunctival injury: Improper application technique during use of the eye drops may cause damage to the conjunctiva, leading to irritation and a burning sensation at the site of injury. Medical attention should be sought promptly in such situations.

In addition, using naphazoline, chlorpheniramine and vitamin B12 eye drops when the eyes are already fatigued may also lead to a burning sensation.