There’s some evidence that vitamin C, also known as ascorbic acid, may help with some allergies. Vitamin C acts as a natural antihistamine and antioxidant. Studies have shown it may decrease inflammation, swelling, and related symptoms that happen at the site of an allergic reaction.
Allergy symptoms happen when your immune system reacts to a foreign invader, called an allergen. Common allergens include pollen, pet dander, and proteins in certain foods. Cells in your immune system called mast cells are activated and release histamine to help block the invader. Histamine may trigger the following allergy symptom: runny nose, sneezing, red and watery eyes, itching and rash.
For mild seasonal or environmental allergies, antihistamine medications can block histamine and its effects, but they can have unwanted side effects of their own. Vitamin C acts differently from antihistamine medications, reducing the amount of histamine you produce rather than blocking histamine receptors. Research suggests histamine levels may reduce by about 38% after a person takes 2 grams of vitamin C.
As with most supplements, it is important to consult your physician before you take anything new.