The medication should not be used in pets with hypersensitivity, glaucoma and urinary retention related medical problems. Extreme caution is required when used in seizure prone animals. Drug interactions are reported with the usage of Doxepin. The medication should not be used with monoamine oxidase inhibitors, sedatives, antihistamines, norepinephrine, thyroid medications, atropine, and phenytoin. It is recommended to inform the veterinarian about the medications the pet is taking.