Can something you're allergic to be a temporary allergy?

My mom grew up eating crab in the Philippines.  She had a crab allergy when i was growing up till i was 18.  Not she can eat crab just not too much, crab sensitive, not allergic

Depends on what you mean by "temporary." Childhood allergies can certainly improve or even disappear over time, but it takes many years. Most allergies acquired in adulthood don't diminish, but become worse.

Don’t confuse allergy with a side effect or a simple reaction. Otherwise, it’s impossible to speculate without knowledge. Some simple allergies you can grow out off, or you may not be exposed to the allergen anymore. Allergies are complicated and not all are triggered the same.

No, you will suffer with this for life.