This article details the known side effects, relief measures, and storage requirements of Sancoba ophthalmic solution (a ciliary function-improving eye drop) to help users use this product safely and properly.

I. What are the side effects?

1. Known types of side effects

The frequency of side effects for this product is classified as "unknown". Currently, the only confirmed side effect is allergic symptoms (allergy/allergic symptoms).

2. Specific manifestations of allergic symptoms

(1) Allergic symptoms mainly include: eyelid redness/swelling, conjunctival hyperemia, eye itching, foreign body sensation, increased tearing, etc.

(2) In rare cases, periorbital skin rash may occur.

3. Characteristics of side effects occurrence

(1) The incidence is extremely low, consistent with the low allergenicity of vitamin B12 itself.

(2) May occur with first-time use or long-term use; individuals with allergic predisposition are at relatively higher risk.

(3) Symptoms are usually mild and resolve spontaneously upon discontinuation.

4. No other systemic side effects

As this product is for topical ophthalmic use, systemic absorption is extremely low (rabbit eye studies show intraocular transfer rate up to only 1.286%). Therefore, it does not cause systemic side effects such as gastrointestinal, neurological, or hematological effects.

II. Ways and methods to relieve side effects

1. Primary measures after allergic symptoms appear

(1) Discontinue instillation immediately.

(2) The earlier the discontinuation, the faster the symptom relief.

2. Local irrigation

(1) If significant irritation persists after discontinuation, gently rinse the conjunctival sac once or twice with sterile saline or cooled boiled water to help remove residual solution.

(2) Avoid rubbing the eyes vigorously.

3. Cold compress to relieve itching

(1) For mild eye itching and redness/swelling, apply a clean towel wrapped around an ice pack to the closed eyelids for 5-10 minutes, 2-3 times daily.

(2) Cold compress constricts blood vessels, reduces hyperemia and itching sensation.

4. When to seek medical attention

It is recommended to visit an ophthalmologist in the following situations:

(1) Symptoms do not improve or worsen within 24 hours after discontinuation and cold compress.

(2) Decreased vision, increased eye pain, or increased discharge occurs.

(3) Rash spreads to other parts of the face or is accompanied by difficulty breathing (extremely rare, indicating a severe allergic reaction).

5. Management when seeing a doctor

(1) The doctor may prescribe anti-allergic eye drops (e.g., ketotifen fumarate eye drops, olopatadine eye drops) or short-term use of corticosteroid eye drops.

(2) Oral antihistamines (e.g., loratadine) are generally not needed, as symptoms are localized.

6. Preventing recurrence

(1) Once allergy to this product is confirmed, record it and inform your doctor to avoid reusing eye drops containing cyanocobalamin or similar preservatives (benzalkonium chloride).

(2) Preservative-free, single-dose vitamin B12 eye drops (if available) may be tried, but cross-allergy is still possible.

III. Storage conditions

1. Storage temperature

(1) Store at room temperature.

(2) Do not refrigerate (2-8°C may cause crystallization), do not freeze (destroys formulation stability), do not store at high temperatures (e.g., in a car during summer or near a heater).

2. Light protection requirement

(1) This product is a clear red solution; the active ingredient cyanocobalamin is light-sensitive.

(2) It is recommended to keep it in the original carton, avoiding direct sunlight and strong indoor light sources (e.g., bathroom heaters, UV disinfection lamps).

(3) Light protection is also required after opening.