Dr. Barry Dworkin

Originally published in The Ottawa Citizen May 20, 2003
Original Title: How to Produce a Natural Allergy

Proteins in some plants and products so closely resemble pollen antigens, they can confuse the immune system, trigger allergic reactions.

It’s spring and that means allergies are again exacting their seasonal vengeance.

Many people don’t know it, but pollen allergies can increase the risk of severe allergic reactions to other plants, foods and herbal or naturopathic remedies.

The proteins (antigens) within these plants and products resemble pollen antigens: the proteins that trigger an allergic reaction. The similarity can confuse the immune system, causing an allergic response.

This cross-reactivity of antigens in an unsuspecting person is an important concept in allergy and immunology. For example, a person allergic to birch pollen may have an allergy to apples.

• Fifty to 90 per cent of people allergic to birch pollen can react to nuts, fruits such as kiwi, apples, pears and plums and vegetables like potatoes, tomatoes, celery and carrots.
• Grass pollen has a cross-reaction relationship with carrots, potatoes, celery, tomatoes, buckwheat, melons, oranges and Swiss chard.
• Ragweed sufferers should be careful about zucchini, cucumbers, bananas, melons (cantaloupe, honeydew and watermelon), apples, chamomile tea, honey, nuts and sunflower seeds.
• Some foods will cause oral allergy syndrome in people afflicted with airborne allergies. The symptoms include a raw, itchy rash around the mouth. Some people develop a full-blown allergic reaction.

In the spring 2003 edition of the Allergy and Asthma News, Ottawa allergist Dr. Antony J. Ham Pong writes about allergies to herbal products: Hay fever (ragweed allergy) sufferers are at risk of severe allergic reactions or anaphylaxis if they use certain herbal and naturopathic remedies.

• Chamomile, feverfew and echinacea belong to the compositae plant family, which includes ragweed, goldenrod, chrysanthemum, sunflower, sagebrush, mugwort, marigolds and daisies.
• Chamomile, used as a digestive aid, to treat menstrual cramps, as an enema preparation and as a topical antibiotic, increases the risk of anaphylaxis and death.
• Echinacea, considered by some to be an immune booster and to treat allergies and colds, can itself cause anaphylaxis, allergic skin rashes and asthma attacks. Feverfew, used to treat migraine headaches, produces similar reactions.
• Bee honey, a food tonic, can contain pollen grains and antigens leading to hives, an itchy mouth and throat and anaphylaxis.
• Royal jelly — the secretion from worker honeybees — may contain compositae pollens and may cross-react with dust mites.

Several products interact with standard allergy medications: the antihistamines and decongestants. They can augment the sedating effects of antihistamines found in cough and cold remedies like dephenhydramine (Benadryl), hydroxyzine (Atarax) and chlorpheniramine (Chlor-Tripolon).
Kava’s sedating effects are used to treat anxiety, stress and insomnia. Unfortunately, it can lead to excessive sedation and poor co-ordination when combined with certain antihistamines. Health Canada does not recommend its use because it can cause severe liver toxicity.
Valerian can cause similar side effects as Kava.

• Ephedra is used to treat asthma, colds, hay fever, obesity and for bodybuilding. Using decongestants like pseudoephedrine (Sudafed) in combination with ephedra can cause dizziness, headaches, irregular heart rhythms, increased blood pressure, seizures, tremors, strokes and death. Health Canada also issued a warning about ephedra.
• Cross-reactivity may explain why workers such a nurses who use latex gloves often develop an allergy to the gloves. The raw material for latex comes from trees. Latex can cross-react with avocado, kiwi, banana, peaches, chestnuts and melons. Changes in latex production may leave more antigens within the final product, increasing the chance of an allergic response.

According to allergy specialist Dr. Yezdi Patel, people who eat shrimp, celery, carrot or dillweed prior to aerobic exercise may experience an allergic reaction. The mechanism that causes the reaction remains unknown.

Future research may help find better ways to reduce the risk and relieve allergy symptoms. Consult your doctor or pharmacist about potential herbal/drug interactions and allergy risks.