Allergic Conjunctivitis

For other types of allergies, see Asthma and Eczema
About 7% of all Americans suffer from hay fever, an allergic condition that can cause runny nose, sneezing, and teary eyes. It is known officially as allergic rhinitis, allergic sinusitis, or allergic conjunctivitis, depending on whether symptoms manifest mainly in the nose, sinuses, or eyes, respectively. Hay fever usually peaks when particular plants are pollinating or when molds are flourishing. People who suffer from year-round hay fever may be allergic to ever-present allergens such as dust mites.
Heres how hay fever works. In response to the triggers noted above, an individual prone to allergies develops an exaggerated immune response. Substances known as IgEs flood the nasal passages, white blood cells called eosinophils arrive by the millions and billions, and inflammatory substances such as histamine, prostaglandins, and leukotrienes are released in massive amounts. The overall effect is the familiar one of swelling, dripping, itching, and aching.
The mechanism of allergic response is fairly well understood. Why allergic people react so excessively to innocent bits of pollen, however, remains a complete mystery.
Conventional treatment for hay fever consists of antihistamines (now available in forms that dont make you sleepy), leukotriene inhibitors, decongestants, nasal steroids, cromolyn sodium, and allergic desensitization (\"allergy shots\"). For most people, some combination of these treatments will be successful.

Proposed Treatments for Allergies:
The following treatments are widely recommended for allergies, but they have not been scientifically proven effective at this time.
Butterbur
The herb butterbur is best known as a promising new treatment for @migraine headaches@. However, a recent study provides preliminary evidence that it might be useful for allergies too. This two week double-blind study of 125 individuals with hay fever (technically, "seasonal allergic rhinitis") compared a standardized butterbur extract against the antihistamine drug certizine. According to ratings by both doctors and patients, the two treatments proved about equally effective.
The lack of a placebo control group diminishes the meaningfulness of this study, but these are nonetheless promising results.
Nettle Leaf
According to one preliminary double-blind placebo-controlled study, freeze-dried extract of stinging nettle leaf can at least slightly improve allergy symptoms.
For more information, including dosage and safety issues, see the full nettle article.
Quercetin, OPCs, and Other Flavonoids
Test tube studies suggest that flavonoids—biologically active compounds found in many plants—may help reduce allergy symptoms. A particular flavonoid, quercetin, seems to be one of the most active. Many texts on natural medicine claim that quercetin works like the drug cromolyn (Intal) by stopping the release of allergenic substances in the body. However, while we have direct evidence that cromolyn is effective, there have not been any published studies in which people were given quercetin and their allergic symptoms decreased. It is a long way from test tube studies to real people.
OPCs from grape seed or pine bark are also often said to be effective. However, an 8-week double-blind trial of 49 individuals found no benefit with grape seed extract (dose not stated).
Vitamin C
Vitamin C is often suggested as a treatment for allergies, but the research results are very preliminary and somewhat contradictory.
Other Treatments
Highly preliminary evidence suggests spirulina may counter allergic reactions.
Bee pollen, vitamin B6, vitamin B12, cats claw, Coleus forskohlii, GLA, fish oil, MSM, and betaine hydrochloride are sometimes recommended for hay fever, but there is as yet no significant evidence that they are effective.