How Is Conjunctivitis (Pink Eye) Diagnosed? Tests, Criteria & Process
Conjunctivitis (Pink Eye) diagnosis relies on Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis. Learn the full diagnostic pathway, clinical criteria, differential workup, and what to expect at your evaluation.
Updated March 27, 2026
Conjunctivitis (Pink Eye) is diagnosed using Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis and targeted clinical evaluation. Conjunctivitis is inflammation of the conjunctiva causing redness, discharge, and irritation. Bacterial conjunctivitis produces purulent discharge (antibiotic drops); viral is watery (self-limiting); allergic causes itching (antihistamine drops).
Clinical Context
The diagnostic process for Conjunctivitis (Pink Eye) begins with Thorough history and physical examination followed by basic blood and urine tests; targeted specialist investigation as needed. Key investigations include Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis, Chest X-ray. The gold standard is: Directed investigation based on clinical history and physical examination findings. Clinical guidelines from NICE / BMJ Best Practice / WHO define the diagnostic criteria and recommended investigation pathway.
Clinical Pathway
Conjunctivitis (Pink Eye) — Full Condition GuideCondition HubConjunctivitis (Pink Eye) — Differential DiagnosisDifferentialConjunctivitis (Pink Eye) — Treatment PathwaysTreatmentConjunctivitis (Pink Eye) — Prognosis & OutlookPrognosisFrequently Asked Questions
How Is Conjunctivitis (Pink Eye) Diagnosed? Tests, Criteria & Process?+
Conjunctivitis (Pink Eye) is diagnosed using Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis and targeted clinical evaluation. Conjunctivitis is inflammation of the conjunctiva causing redness, discharge, and irritation. Bacterial conjunctivitis produces purulent discharge (antibiotic drops); viral is watery (self-limiting); allergic causes itching (antihistamine drops).
How do doctors test for conjunctivitis (pink eye)?+
The main tests used to diagnose Conjunctivitis (Pink Eye) include Full blood count (FBC), Comprehensive metabolic panel (electrolytes, creatinine, LFTs), Urinalysis. Your doctor will select investigations based on your symptoms, clinical findings, and risk factors.
How long does it take to diagnose Conjunctivitis (Pink Eye)?+
The time to diagnosis varies. Some cases are identified within hours using clinical presentation and blood tests; others require weeks, repeated investigations, or specialist referral.
Can Conjunctivitis (Pink Eye) be missed on initial testing?+
Yes — Conjunctivitis (Pink Eye) can be missed if initial tests are negative or if the presentation is atypical. If clinical suspicion remains high, repeat testing or specialist referral is appropriate.
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