① Respiratory infections: viral and mycoplasma infections are the most common triggers in infancy and early childhood. ② Inhalant allergens: dust mites animal fur and excrement cockroaches, fungi, plant pollen, dust, smoke, paint, perfume and other chemical gases. Dust mites are the most common trigger of allergic asthma in the southern region. ③ Food allergens: milk, fish and shrimp, eggs, peanuts, seafood and other heterogeneous proteins. ④ Contact allergens: cosmetics, gasoline, paint, alcohol, etc. ⑤ Strong emotional changes; exercise and hyperventilation; cold air; certain medications especially early intravenous medications for infants. In conclusion older children are prone to inhalation allergies and infants are prone to respiratory infections or food allergies.