I have was recently diagnosed with a cat allergy. For the past week Ive had a feeling of fullness in my head and some sinus pressure. Is the fullness and lightheadedness a symptom of allergies?

It certainly is. you might want to try saline nasal spray to help with your allergies. I use it for my allergies and it helps me a lot and is very safe.

Yes it can be,but also suggests a possible sinus infection.Invest in a neti pot which is a pot designed to be filled with salt water and irrigated through your sinus passages,by pouring the spout through one nostril and out the other.this will wash any allergens,danders or irritants from your sinus cavities,its completely safe and highly recommended by physicians.

netipot.com