You should see an Allergist if:

Your allergies are causing symptoms such as chronic sinus infections, nasal congestion or difficulty breathing.
You experience hay fever or other allergy symptoms several months out of the year.
Antihistamines and over-the-counter medications do not control your allergy symptoms or create unacceptable side effects, such as drowsiness.
Your asthma or allergies are interfering with your ability to carry on day-to-day activities.
Your asthma or allergies decrease the quality of your life
You are experiencing warning signs of serious asthma such as: You sometimes have to struggle to catch your breath.
You often wheeze or cough, especially at night or after exercise.
You are frequently short of breath or feel tightness in your chest.
You have previously been diagnosed with asthma, and you have frequent asthma attacks even though you are taking asthma medication.