shuō “wǒ guòmǐn” hái búgòu, zuìhǎo shuōmíng duì shénme guòmǐn, yǐqián yǒu shénme fǎnyìng

说“我过敏”还不够，最好说明对什么过敏、以前有什么反应。

Just saying 'I have an allergy' isn't enough; it's best to specify what you are allergic to and what reactions you've had in the past.