Must not be used if you are hypersensitive to any of their ingredients or by children under 6 years of age. In very rare cases, adverse reactions such as hypersensitivity, stinging, excessive tearing, pain, feeling of a foreign body in the eye, or other temporary local irritations have been reported, which disappeared upon discontinuation of use of HYLO DUAL®. Temporary blurred vision may occur after use. In very rare cases, this may cause temporary headaches in sensitive patients.