This is a condition in which the small bronchial airways temporarily constrict, so that it is difficult to exhale. This leads to breathlessness and wheezing. Such difficulty is caused by muscle spasm in the bronchi of the lungs. This narrows the space available for air to make its way out of the lungs, and breathing out is always more difficult than breathing in, thus producing the characteristic wheezing sound associated with asthma attacks.

Because the passages are narrowed and air flow reduced, mucus also builds up in the lungs, and this makes it even more difficult to breathe. The mucus is also a breeding-ground for bacteria, so attacks of bronchitis may arise as a complication of the asthma.

Many asthma attacks are triggered by allergens, such as dust, mould spores, mites, animal hair or feathers but the onset may equally be caused by cold air, or it may be preceded by an infection such as a cold. Certainly, stress and more specifically acute anxiety are known to be the immediate trigger for many attacks, and this can sometimes give rise to a vicious circle of asthma - anxiety about the asthma - further attacks. Thus a wide range of etiological factors can be involved in this all too common problem. A number of different groupings can be applied:

• extrinsic asthma - caused by allergic responses to house dust, animal fur, or various foods. Such causes 10-20% of adult asthma.
• intrinsic asthma - caused by genetics, structural problems, infections, pollutants and stress - both physiological and psychological. Such causes 30-50% of adult asthma.

1. Mild - mild dyspnoea; diffuse wheezes; adequate air exchange.
2. Moderate - respiratory distress at rest; hypernea, use of accessory muscles; marked wheezes.
3. Severe - marked respiratory distress; cyanosis; use of accessory muscles; marked wheezes or absent breath sounds.
4. Respiratory failure - Severe respiratory distress; lethargy; confusion; prominent pulsus paradoxus. Use of accessory muscles.

• Inhaled allergens - Commonly inhaled allergens include the house-dust mite; animal dander's; pollens, particularly grass; mould spores.
• Irritant gases - including cigarette smoke.
• Ingested allergens - foods; drugs, e.g. aspirin, colored medicines(pills, capsules and syrups); food additives; yeast and moulds on food.
• Infecting organisms - either due to the infection itself or an allergy to the organism.
• Temperature changes - especially cold air.
• Changes in the weather.
• Exercise.
• Emotional stress - e.g. bereavement.
• Hormonal changes.
• Certain chemicals in the workplace.

Pulmonary tonics are important in long term strengthening of the lungs, but will do little in short term relief of an attack.
Expectorant remedies will be essential to ensure that there is the minimum of build up of sputum in the lungs. However, stimulant expectorants would potentially aggravate the breathing difficulties. Thus only use relaxing expectorants.
Demulcents will be soothing and support the relaxing expectorants.
Anti-spasmodic plants will ease the spasm response in the muscles of the lungs.
Anti-microbial support is called for if there is potential for secondary infection, which is too be guarded against at all costs.
Anti-catarrhals aid the body in dealing with overproduction of sputum in lungs or sinuses.
Cardio-Tonic herbs will support the heart in the face of lung congestion or strain.
Nervine support is always appropriate either because stress is a trigger or because the asthma becomes a source of stress & concern which then in turn triggers attacks.