Never had allergies growing up, now in my 20s feels like i have bad allergies all the time. can't go a day without claritin (loratadine) & still stuffy when on it ?

See an allergist: Allergies can develop at any age but especially in young adults. Seasonal symptoms are typically triggered by pollen allergy, while symptoms during the winter or daily symptoms suggest an indoor allergy. Claritin is helpful for itching, sneezing and nasal drainage, but not stuffiness. An allergist can help identify the trigger and develop a individualized treatment plan that gives relief.

That can happen: Unfortunately as our bodies change and the seasons and global climate changes as well, we can develop allergies later in life. If they become unbearable, see an allergist and get properly diagnosed and treated. Best wishes.