Many asthmatics have severe aggravation in their condition due to allergies to certain allergens. Common allergens causing asthma are:

Plant Pollens: Pollen grains are the powdery substance produced by the plants for the process of reproduction. Individual pollen grains are very small in size so collectively they appear as a powdery substance. Pollen grains of different plants are of many different shapes and sizes. They get disseminated by wind, water or animal sources to far and wide places. Some people are allergic to pollens of some plants. Since the pollen emergence is seasonal their allergy is also seasonal.

It is mostly seen that the pollen that get disseminated with wind cause allergic asthma in people. Generally the flowers of plants that have wind disseminated pollen are unattractive in appearance and smaller in size. Pollens are generally released early in the mornings, often before sunrise. Many patients who are sensitive to them also develop symptoms around that time. For allergic people it is important to know the pollen calendar of a place before one has plans to settle down there, or is only visiting the place, if one is susceptible to pollen allergies. It is also recommended to keep the windows closed and prefer to be in air conditioned atmosphere.

Fungi: Fungi are saprophytic plants that are very small in size. So they appear as fibrous growth on the surfaces they grow. They are basically scavengers and help in decay and break up of dead organisms into basic chemical components. Some fungi are very useful and are put to various uses. Antibiotics like penicillin and streptomycin are made from them. Various mushrooms are fungi varieties. Alcohol, wine, cheese and various bakery products made by the process of fermentation are made by the use of many fungi. They propagate mostly by vegetative growth.

The spores produced in the process are released as powdery substance. Some people are allergic to these spores. They cause allergic asthma in people. It helps to study the fungal calendar just as in the case of pollens. The peak periods of fungal spore concentration are the months of September to November and February to April. The people who are allergic to various fungi may show allergic reactions even after consumption of foods containing them. Mushroom allergy is known to be very common.

The people suffering with fungi allergies should take additional precautions apart from following the fungal calendar. They should avoid any accommodation in basements of buildings whether for official or residential purposes. Plastered and painted walls should be preferred instead of wall papered ones, which may catch moisture faster. All rooms and spaces should be very well ventilated. Potted plants should be avoided inside living spaces.

House Dust: Many people are allergic to house dust. The dust that settles over the various furniture and furnishings in the house is collectively called house dust. It may comprise of the outside dust and also the various kinds of dust that originate inside the house. It may be from food remnants, from the pets, from insects in the house, from human hair and skin and many other such sources.

The house collects more in carpets, beddings, old furniture, and other nooks and crannies. Normally such dust is not visible. It can be seen in the shaft of sunlight entering a room. The people who are allergic dust are actually shown to be allergic to mites occurring in the dust. The most common house dust mite is named Dermatopagoides pteronyssinus. These mites live and feed on the components of the house dust. Those who are allergic to house dust should keep their living spaces scrupulously clean. They should avoid putting too much of furniture and heavy furnishings in their rooms.

Food Articles: Many people are allergic to different food articles. Different symptoms may be caused in different people allergic to various foods like gaseous distension, diarrhoea, urticaria, headache, swelling of lips, sores in the mouth cavity and many others. Sometimes the symptoms appear immediately and sometimes they take a while to manifest. Also the food allergies may be dependent upon the seasonal changes. Many infants are allergic to milk especially cow's milk. Wheat, fish, egg and mushrooms are common food allergens. The diagnosis is dependent upon elimination diets as skin tests are generally of not of much help.

Insects: Insect bites normally cause pain and swelling due to the introduction of insect venom inside the system. The degree of manifestation of symptoms depends upon the quantity of venom. The insects can be of two types the stinging insects and the biting insects. However the symptoms are never fatal. Some people are allergic to remnants of insects.

Animals: Many people are allergic to different animals among these most common ones are domestic animals like cats and dogs. Other animals may be horses, cows, buffaloes and other fur bearing animals. The allergy is mostly caused by animal dander.

Occupational allergens: Many people are allergic to substances that they may come in contact on account of their occupation. Some common examples are bakers getting allergic to flour, cement workers allergic to cement, sulphur allergy in workers in different medicine factories, workers allergic to leather dust and hairstylists and beauticians allergic to various chemicals in beauty products.