Must not be used if you are hypersensitive to any of their ingredients. In very rare cases, hypersensitivity reactions such as stinging or excessive tearing have been reported, which disappeared immediately after discontinuing use of HYLO PARIN®. In very few cases, allergic skin reactions due to heparin have been reported. If eye drops containing gentamicin must be applied at the same time, wait at least one hour between applications to avoid the formation of visible precipitates in the conjunctival sac.