DefinitionCausesWhen to see a doctorDefinitionBy Mayo Clinic StaffRed eye is a common problem that can happen in one or both eyes. The redness comes from the blood vessels on the surface of the eye. These blood vessels expand due to irritation or disease.From Mayo Clinic to your inboxSign up for free and stay up to date on research advancements, health tips, current health topics, and expertise on managing health. Click here for an email preview.EmailTo provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.CausesShareTweetFeb. 19, 2025Eye pain. Merck Manual Professional Version. https://www.merckmanuals.com/professional/eye-disorders/symptoms-of-ophthalmic-disorders/eye-pain. Accessed Oct. 17, 2024.Jacobs DS. The red eye: Evaluation and management. https://www.uptodate.com/contents/search. Accessed Oct. 17, 2024.Ferri FF. Differential diagnosis. In: Ferri's Clinical Advisor 2025. Elsevier; 2025. https://www.clinicalkey.com. Accessed Oct. 17, 2024.Leonardi A, et al. Office-based ocular procedures for the allergist. Current Opinion in Allergy and Clinical Immunology. 2019; doi:10.1097/ACI.0000000000000563.Pain in eye. American Academy of Ophthalmology. https://www.aao.org/eye-health/symptoms/pain-in-eye-3. Accessed Oct. 17, 2024.Skorin L, et al. Ectropion: Classification, diagnosis, and management. Consultant. 2018;58:e180.Walls RM, et al., eds. Red and painful eye. In: Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Elsevier; 2023. https://www.clinicalkey.com. Accessed Oct. 17, 2024.Dry eye. American Academy of Ophthalmology. https://www.aao.org/eye-health/diseases/what-is-dry-eye. Accessed Oct. 17, 2024.Eye infections from contact lenses. American Academy of Ophthalmology. https://www.aao.org/eye-health/diseases/contact-lens-related-eye-infections. Accessed Oct. 17, 2024.Bonini S. The red eye. European Journal of Ophthalmology. 2021; doi:10.1177/11206721211024827.Salinas R, et al. Floppy eyelid syndrome: A comprehensive review. The Ocular Surface. 2020; doi:10.1016/j.jtos.2019.10.002.Injections to treat eye conditions. National Eye Institute. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/diabetic-retinopathy/injections-treat-eye-conditions. 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