Antihistamine Eye Drops for Subconjunctival Hemorrhage
Do not use antihistamine eye drops for subconjunctival hemorrhage unless the patient has concurrent allergic conjunctivitis causing the itching. Subconjunctival hemorrhage itself does not cause itching—it is a benign, self-limited bleeding under the conjunctiva that typically presents with redness but without pain, discharge, or itching 1. If itching is present, you are likely dealing with a separate condition (allergic conjunctivitis) that happens to coexist with the hemorrhage.
Clinical Algorithm for Itchy Eye with Subconjunctival Hemorrhage
Step 1: Determine the Source of Itching
- Subconjunctival hemorrhage alone does not cause itching 1
- If itching is present, look for signs of allergic conjunctivitis: watery discharge, bilateral involvement, history of atopy, seasonal pattern, or other allergic symptoms 2, 3
- The hemorrhage and allergic conjunctivitis are two separate processes that may coincidentally occur together
Step 2: If Allergic Conjunctivitis is Confirmed
First-line treatment for the itching:
- Refrigerated preservative-free artificial tears 2-4 times daily to dilute allergens and inflammatory mediators 3, 4
- Cold compresses for immediate symptomatic relief 3, 4
- Dual-action antihistamine/mast cell stabilizer drops (olopatadine, ketotifen, epinastine, or azelastine) twice daily provide rapid onset within 30 minutes and are suitable for both acute and long-term treatment 2, 3, 4
Important safety consideration: These antihistamine drops will not harm the subconjunctival hemorrhage and can be used safely if allergic conjunctivitis is the cause of itching 5, 6.
Step 3: If No Clear Allergic Conjunctivitis
- Do not prescribe antihistamine drops if there are no signs of allergic disease
- Reassure the patient that subconjunctival hemorrhage is benign and self-resolving, typically within 1-2 weeks 1
- Investigate other causes of itching: dry eye, blepharitis, or contact lens-related irritation 1
Critical Pitfalls to Avoid
- Never assume itching is from the hemorrhage itself—this is a diagnostic error that leads to inappropriate treatment 1
- Avoid topical vasoconstrictors (naphazoline, tetrahydrozoline) as they can cause rebound hyperemia if used beyond 10 days and provide no benefit for hemorrhage resolution 2, 4
- Do not use topical antibiotics—they provide no benefit for either subconjunctival hemorrhage or allergic conjunctivitis and can induce toxicity 4
- Avoid oral antihistamines as primary treatment for ocular allergy symptoms, as they may worsen dry eye and are less effective than topical agents 2, 4
When to Investigate Further
If subconjunctival hemorrhage is recurrent or persistent, evaluate for systemic hypertension, bleeding disorders, anticoagulant use, systemic malignancies, or ocular tumors 1. The presence of itching does not change this workup algorithm.