There are two main types of asthma drugs, short-acting or quick-relief medications (also called "rescue" drugs), and long-term control drugs.

The most common method of delivering asthma medications is through the use of inhalers. It is important to know that not all inhalers are short-acting drugs; in many cases long-term control drugs are also delivered using an inhaler. To treat an occasional asthma attack, you'll use a short-acting drug. If you only have occasional symptoms, this may be the only type of medication you need, but even people with moderate to severe asthma need to keep a quick-relief drug handy in case of an attack.

Long-acting drugs, including some kind of inhalers, are used to control and prevent symptoms in people with persistent asthma (who have symptoms at least twice a week). The recommended dose may change over time, depending on how severe your asthma is. These drugs are usually anti-inflammatory, working to prevent the immune reactions that cause asthma symptoms in the first place.

Quick-relief drugs are bronchodilators -- they usually work on the nervous system's autonomic (involuntary) nerve pathways, causing them to relax the muscles in the airways. They work by mimicking other chemicals that would normally act on these types of nerves; specifically, they bind to a nerve receptor to either intensify a natural reaction or block it. (A receptor is a type of gateway or "docking station" that only certain chemicals can fit into).

Beta-2 agonists: These are the most common quick-relief asthma medicines. An agonist is something that "turns on" a reaction when it lands in the right place -- it's the opposite of an antagonist. Beta-2 agonists are a class of chemicals that include adrenaline, which controls your body's responses to stress. Beta-2 agonists bind in the tissues around your airways, and this sets off a reaction that relaxes the muscles in your bronchial tubes and helps you breathe easier.

Short-acting inhaled beta-2 agonists start to work within 5 minutes and the effects can last up to 3-8 hours. You can use it as symptoms appear, and about 20 minutes before exercising to prevent exercise-induced asthma symptoms. (There are also longer-acting forms used for long-term control.)

Side effects of inhaled beta-2 agonists are usually milder than the oral form used for long-term control. Common side effects of the inhaled form include shakiness (tremors), faster heart rate, restlessness, anxiety, sleeplessness, headache, and muscle cramps. Different drugs have slightly different sets of side effects.

Cautions: If you overuse this type of drug, that's a sign that you may need more controller medication, without which your asthma symptoms may get worse instead of better. Be sure to let your doctors know if you have a history of angina, heart disease, high blood pressure, stroke or seizure, diabetes, thyroid disease, prostate disease, or glaucoma.

Interactions: Other drugs may increase the effects of oral beta-2 agonists, including certain antidepressants, thyroid drugs, other bronchodilators (oral or inhaled), and antihistamines. If you're also taking methylxanthines (see below) for long-term control, you may feel more of the effects on your heart. Beta blockers, used to treat heart disease, can decrease the effect of these drugs. Oral beta-2 agonists, in turn, can interfere with drugs that reduce blood pressure and with digitalis drugs, used to treat congestive heart failure and very rapid heartbeat.

Anticholinergics: These drugs work by blocking a type of acetylcholine receptor in the tissues of the lungs, which causes bronchial muscles to relax and reduces the amount of mucous produced. Anticholinergics work through the cholinergic branch of the involuntary nervous system, which in conjunction with the autonomic nervous system, controls your heartbeat, breathing, and other core "housekeeping" activities.

This type of asthma medication comes in an inhaler and is usually used in conjunction with other medicines for severe asthma attacks because it takes longer to act. It can be used as the primary reliever medication for some patients with chronic obstructive pulmonary disease (COPD) like emphysema, or for those who have post-infectious cough. (It's also used for long-term asthma control sometimes, but it's not common.)

Side effects are uncommon and usually mild. The most common ones include dry mouth, blurred vision, sensitivity to light, and throat or mouth irritation.

Cautions and interactions: This medication has no known drug interactions.

Oral Corticosteroids: While they don't provide quick relief, oral corticosteroids (a class of anti-inflammatory drugs) are sometimes used to stabilize symptoms when an asthma attack strikes. Corticosteroids interfere with inflammation, which is often the immune system's natural response to an irritant or invader. For this reason, a course of corticosteroid pills is often recommended to fight inflammation.

For more details on the effects, side effects, and interactions of corticosteroid drugs, see the full listing under long acting drugs, below, and the entry in the table for long-acting drugs.

Asthma is now understood to be a chronic inflammatory disorder of the airways in which many types of cells play a role.

Controller drugs are usually anti-inflammatory -- they help to control the immune reactions that cause asthma attacks, thus preventing them from happening at all. Some long-acting bronchodilators are also used for long-term control.

Beta-2 agonists, long-acting: These drugs work the same way as the short-acting beta-2 agonists, and are often used together with a corticosteroid to provide long-term control. Used alone, they have minimal anti-inflammatory activity. The long-acting beta-2 agonists start working in 3 to 30 minutes and last for at least 12 hours after a single dose.

Side effects: Common side effects of long-acting beta-2 agonists include restlessness, anxiety, sleeplessness, shakiness (tremors), and headache. Different drugs have slightly different sets of side effects -- although the Food and Drug Administration warns that all of these medications may increase the chance of a severe asthma episode, possibly leading to death.

Cautions: Do not take more than the prescribed amount of long acting beta-2-agonists. They should also not be used alone for long-term asthma control. These agents are not designed for "as needed" use and over-use could result in an over-dose. A safety study of the drug Serevent (salmeterol xinafoate) involving more than 25,000 subjects found that the drug may be associated with a very slight increase in serious asthma episodes and deaths, particularly in African Americans. The increase was not statistically significant, and the Food and Drug Administration strongly advises patients on the medication not to stop taking it without talking to their doctors. However in 2006, the FDA did issue its strongest caution, a "Black Box" warning, for long-acting beta-2 agonists like Serevent, Advair Diskus, and Foradil. Further investigation of possible risks is planned. For more details on cautions and side effects of asthma drugs, see the listing under short-term medicines, above, and the entry in the table below.

Inhaled Corticosteroids: These are anti-inflammatory medications that interfere in a broad way with the immune system and are used to control many types of inflammation, which is simply the immune system's response to an irritation or invader. In asthma treatment, corticosteroids reduce the immune system's response to triggers in the airways and prevent the resulting inflammation. That accounts for the reduction in inflammation symptoms, such as airway hypersensitivity, swelling inside the airway muscles, and mucus and secretions in the lungs.

Side effects:

Inhalers:
Corticosteroids come in inhalers and pills. Common side effects of the inhaled form include dry mouth, throat irritation, hoarseness, rash, and thrush (yeast infection in the mouth). They can be used in short bursts, in oral form to get symptoms under control after an attack, or as long-term prevention (usually in the inhaled form, but sometimes oral as well in severe asthma) for people with persistent asthma.

Pills:
The most common side effect of short-term pill dosages is an upset stomach, which can lead to or aggravate a stomach ulcer. Other common ones includechange in appetite, emotional lability, water retention, muscle weakness, potassium loss (tiredness, weakness, muscle cramps), slower wound healing, increased blood sugar, sweating, rash, itchiness, headache, dizziness, and convulsions. Because corticosteroids act by interfering with the immune system, it's easier to catch infections while taking them and harder to recover from new or existing infections. For the same reason, don't get any vaccines without consulting your doctor first.

The effects of long-term use, especially on high doses of pills, can include adrenal suppression, bone loss, caratacts, glaucoma, stomach ulcers, thinned skin, hair loss, "moon face," menstrual irregularities, and "steroid psychosis" -- symptoms can include mood swings, sleeplessness, personality changes, and depression. There are many other side effects from long-term use, so if you notice any unusual symptoms please ask your doctor about them. If you're on long-term corticosteroid treatment, it's very important for your current dosage to be tapered down slowly (even if you're switching to a different form of the medicine) to avoid serious complications such as adrenal insufficiency.

Cautions: Oral corticosteroids should be used with caution in some people, including anyone who's had a recent heart attack and people with osteoporosis, antibiotic-resistant infections (viral and fungal especially), and cancer.

Interactions: Many drugs, including oral contraceptives, can either increase or decrease the effects (and side effects) of corticosteroids, so it's especially important to tell your doctor about all the drugs you're taking, including over-the-counter medicines, and herbs. Corticosteroids may also affect some lab tests.

Mast cells stabilizers: Mast cells are a type of immune cell that carry different chemicals, including histamines, which mediate and aggravate allergic responses. Mast cells tend to spill their contents when there's trouble, and mast cell stabilizers keep that from happening. They're also useful in preventing exercise-induced asthma.

Side effects and cautions: Side effects are uncommon. Skin rash and itching are the most common side effects from the inhaled mast cell stabilizers. Sometimes people experience a dry cough, throat irritation, hives, or nausea after inhaling it. In rare cases, it may cause a severe allergic reaction.

Interactions: This medication has no known drug interactions.

Leukotriene modifiers: Leukotrienes are one type of chemical released by mast calls and other immune cells, and they cause airways to constrict. They also stimulate mucus secretion and fluid buildup, making the airways even narrower. Leukotriene modifiers are designed to prevent leukotrienes from wreaking their havoc.

Side effects and cautions:

Leukotriene receptor antagonists:
The most common side effect of these drugs is headaches, and other common side effects include nausea, diarrhea, and infections. Aspirin increases the amount of the drug in the bloodstream, while theophylline and certain antibiotics can decrease its effect. People with liver damage may need a lower dose.

5 Lipoxygenase inhibitors:
The most common side effect is headache, followed by general pain, nausea, upset stomach, and liver inflammation. Zileuton can cause lowered white blood cell counts. People with active liver disease should avoid it altogether, and if you're taking it, you'll need periodic blood tests to check how your liver and blood counts are doing.

Interactions: Both types of leukotriene modifiers enhance the blood levels of many other drugs, so be sure to tell your doctor of all the medications you're on.

Methylxanthines (Xanthine bronchodilators): This class of drugs includes theophylline, a stimulant similar to caffeine but far more powerful. Theophylline relaxes the muscles around the airways, but we don't know exactly how. Because these drugs cause many side effects, they're less often a first choice for long-term asthma control.

Theophylline and related drugs come in pill and syrup form. They're also available as sustained or timed-release pills so you can take fewer doses in a day. If you have this type of pill, it's important not to chew or crush the pills, or take them with hot food or drinks, because that will release too much of the drug too quickly into the body and cause potentially dangerous side effects.

Side effects: The most common side effects are dose related and occur mostly when blood levels are high. They include nausea, vomiting, stomachache, diarrhea, restlessness, irritability, headache, trouble sleeping, and faster heartbeat. These drugs can cause or worsen abnormal heart rhythms.

Cautions: You should avoid methylxanthines if you have seizure disorders, and use them with caution if you have a stomach ulcer, heart disease, high blood pressure, or liver disease. If you're on a methylxanthine, you'll need periodic blood tests to monitor your dosage and minimize the side effects from these drugs.

Interactions: Caffeine is a methylxanthine too, so try to minimize the amount of tea, coffee, chocolate, and caffeinated soft drinks you have to keep your dosage within safe limits. Smoking decreases the effects of methylxanthines. Many different drugs can interact with theophylline and related drugs, either increasing or decreasing levels in the blood, so it's especially important to tell your doctor about all the drugs you're taking, including oral contraceptives, over-the-counter medicines, and herbs. Methylxanthines themselves can interfere with other drugs, including sedatives and anesthetics. People with thyroid disorders may need their dose adjusted.

Anti cholinergics: These drugs are sometimes used for long-term control. For more information, see the listing under short-term medicines, above, and the entry in the table below.

Antihistamines: This type of allergy medicine works by blocking histamine, which is released by mast cells. They fight itchiness, redness, and swelling, but they may or may not help your asthma.

Decongestants: These drugs reduce congestion by constricting the blood vessels in the nose, which decreases swelling, and mucus. The most common decongestant is pseudoephedrine (found in Sudafed and many other brand names). It's the synthetic form of ephedrine, the active ingredient in the herb ephedra (known as ma huang in Chinese medicine). Decongestants are stimulants, and the side effects of your other asthma medications (brochodilators) may be magnified if you take them.

Mucolytic agents: These drugs help dissolve excess mucous in the airways, but it's unclear how useful they are in improving asthma symptoms; they may also be irritating to the airway. Available drugs include N-acetylcysteine (Mucomyst).

Further Resources

American Academy of Allergy, Asthma, and Immunology
800-822-ASMA http://www.aaaai.org

American College of Allergy, Asthma, and Immunology
800-842-7777 http://allergy.mcg.edu

American Lung Association
800-LUNG USA http://www.lungusa.org
Asthma and Allergy Foundation of America
800-7-ASTHMA http://www.aafa.org

References

First published November 21, 2001
Last updated December 7, 2007
Copyright © 2001 Consumer Health Interactive

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