Imagine that you really like the smell of certain flowers, like roses or lavender. It makes you happy and feel good. But then, imagine that someone brings a bunch of those flowers into your room and leaves them there all day, every day. At first, you might be happy, but after a while your nose might start to get really stuffy and you might start to sneeze a lot. This is because your body gets tired of smelling those flowers all the time and it starts to have allergies.
That's what happens with perfume, too. Perfume is a mixture of different smells, like flowers, spices, and fruits. Some people love the way perfume smells, but other people have something called perfume allergy. This means that their body doesn't like the smell of perfume and it starts to have allergies.
When someone has perfume allergy, their nose, eyes, and skin start to feel really itchy and uncomfortable when they smell or wear perfume. They might start sneezing a lot or get a headache. Sometimes people with perfume allergy also get a rash or hives on their skin.
So, it's kind of like when you eat too much candy. You might feel happy at first, but then your body gets tired and you feel sick. People with perfume allergy have the same thing happen when they smell perfume too much. It's not because they don't like perfume, it's because their body just can't handle it.