Respiratory allergies are most common, but reactions can also be triggered by certain foods, some types of medicine, insect stings or from the skin coming into contact with certain substances. Some allergies, particularly those caused by pollens, come and go depending on the season, but others, such as house dust mite allergy, are present all year round. Some countries or regions may also have locally-specific allergens. For example, pollen from the local Japanese cedar tree is a common cause of respiratory allergy in Japan.