Many pet owners rely on antihistamines and inhaled or topical corticosteroids for relief. However, prolonged use of these drugs can have unwanted side-effects, including drowsiness, impaired learning and memory, and heart arrhythmias (Ann Allergy Asthma Immunol, 1997; 78: 439-46). Allergy shots also help, but take three to four years to complete and can lead to an allergic response or even anaphylaxis, a life-threatening allergic reaction (Clin Rev Allergy Immunol, 2004; 27: 147-58).
Happily, there are safe alternatives to keep pet allergies under control.
Found in citrus fruits, onions, black tea, apples and lettuce, this inhibits histamine, which contributes to symptoms such as a runny nose and watery eyes. Test-tube studies have found quercetin to be a powerful inhibitor of antigen-stimulated histamine release (Pharmacol Rev, 2000; 52: 673-751), even at low levels (5-50 mmol; 1.51-15.1 mcg/mL) (J Immunol, 1981; 127: 546-50). It's almost twice as effective as the histamine-inhibitor cromolyn sodium, reducing histamine activity by 46-96 per cent (J Allergy Clin Immunol, 1995; 96: 528-36).
Dosage: 250-600 mg, three times daily, five to 10 minutes before meals (Altern Med Rev, 2000; 5: 448-54).
Allergic reactions typically involve an excess of inflammatory prostaglandins (PGs), which contribute to swelling, redness and itching. Bromelain, derived from pineapple, stimulates the production/release of anti-inflammatory PGs while, at the same time, reducing the production/release of pro-inflammatory PGs (Altern Med Rev, 1996; 1: 243-57). Bromelain also enhances the absorption of quercetin (Urology, 1999; 54: 960-3).
Dosage: 400-500 mg three times daily [potency of 1800-2000 MCU (milk-clotting units)] (Altern Med Rev, 2000; 5: 448-54). Allergic reactions may occur in those sensitive to pineapple.
One study has found that 2 g/day of vitamin C lowered blood histamine levels by 38 per cent in just one week (J Am Coll Nutr, 1992; 11: 172-6). In another, vitamin C sprayed into the nose three times a day reduced allergy symptoms (runny nose, blockages, oedema) in 74 per cent of sufferers compared with only 24 per cent of those using a placebo (Ear Nose Throat J, 1991; 70: 54-5).
Dosage: 2 g/day.
Stinging nettle (Urtica dioica)
A randomised, double-blind, placebo-controlled study using 300 mg of freeze-dried nettle for the treatment of allergic rhinitis found that 58 per cent of the users rated it as 'effective' in relieving their symptoms, while 48 per cent found it to be as or more effective than their previous medication (Planta Med, 1990; 56: 44-7).
Dosage: 300 mg/day.
Butterbur (Petasites hybridus)
Although lasting only a week, one recent placebo-controlled clinical study of indoor allergens found butterbur to be as effective as the antihistamine fexofenadine (Clin Exp Allergy, 2004; 34: 646-9). Others have shown butterbur extract (petasin) to be effective for treating hayfever (Int Immunopharmacol, 2002; 2: 997-1006; BMJ, 2002; 324: 144-6).
Dosage: 50 mg twice daily of butterbur extract (containing 8 mg of petasin). Butterbur contains alkaloids that are toxic to the liver, so look for alkaloid-free formulations.