Calcium preparations do not inhibit allergic reactions: a randomized controlled trial

INTRODUCTION Massive consumption of dietary supplements, including vitamins and minerals, has recently become a serious health issue in Europe. Their use may negatively affect the pharmacological activity of various medications, including antiallergic drugs. Calcium preparations are commonly used in some European countries as a popular remedy for allergy‑related skin reactions, such as itching, erythema, and wheals, as well as insect bites. However, so far there have been no reliable studies to prove their action. 
OBJECTIVES The aim of this randomized, double‑blind, placebo‑controlled study was to investigate the efficacy of calcium salts in allergic reactions, using an allergen‑induced skin prick test (SPT). 
PATIENTS AND METHODS Forty adult volunteers with allergic rhinoconjunctivitis or asthma (or both) were recruited to receive oral calcium carbonate (1000 mg) or placebo 3 times a day for 3 days. SPTs were performed with 11 aeroallergen extracts at baseline and at 4 and 72 hours after drug administration. The wheal diameter was measured. We also used the visual analog scale to evaluate the intensity of pruritus.
RESULTS There was no difference in the wheal size or pruritus between patients receiving calcium or placebo at any of the time points (P >0.05). Calcium preparations were well tolerated. 
CONCLUSIONS We found no evidence to support the efficacy of calcium preparations in allergy‑related skin reactions associated with itching and wheals. Calcium preparations do not suppress SPT responses; moreover, their use in allergic patients should be discouraged due to their possible interference with the absorption of antiallergic drugs.