All drugs, even the familiar ones such as aspirin, may have potentially harmful as well as beneficial effects. Whether you are prescribed drug treatment or you choose remedies for yourself, you will gain most benefit from drugs if you understand how they are likely to act and how to use them safely and effectively.
During the last century, advances in drug treatment have enabled doctors to cure many conditions, including a wide range of infectious diseases. Drug treatment can also be used to control symptoms in disorders such as epilepsy and to relieve common symptoms such as itching. Today, there is a vast range of drugs available for many purposes. Some drugs can be bought over the counter, other types require a doctor’s prescription.
The first article in this section covers the types of effect that various drugs may have on the body. The second article gives practical advice on how to use medications effectively and how to store drugs safely.
As recently as 50 years ago, infectious diseases were the leading cause of death in children and young adults. That picture has changed with the introduction of immunization against the major childhood diseases, antibiotics to kill bacteria, and a wide range of other anti-infective drugs.
This section describes the drugs that are used to protect the body against infectious disease as well as to control or cure infections and infestations once they have developed.
The first article discusses vaccines and immunoglobulins, which are given to provide immunity against certain infections and to prevent the spread of diseases. The next article describes antibiotics, a large group of drugs used widely to treat bacterial infections. In the UK, millions of prescriptions are written for these drugs each year.
The following articles in this section explain how drugs are used to treat infections caused by viruses, protozoa, and fungi. The information includes discussion of the prevention and cure of malaria and of recent advances made in the treatment of HIV infection and AIDS. The final article deals with drugs to eradicate parasitic worm infestations.
For more information on the structure and function of infectious organisms, see Viruses.
Drugs acting on the skin are commonly used to relieve dryness and itching, to reduce inflammation, or to treat skin infections and infestations. Most treatments are applied directly to the skin as ointments, creams, or gels. Treatment with oral drugs may be necessary if a skin condition is severe or widespread.
The first article in this section covers emollients and barrier preparations, which are widely used to moisturize the skin and to protect it against the effects of irritant substances. Retinoid drugs, discussed next, are used to treat specific disorders, such as severe acne.
The following two articles in this section cover antipruritic drugs, which are used to relieve itching, and topical corticosteroids, which may be given to reduce inflammation of the skin. Preparations that are applied to the skin to treat infections and infestations are discussed next. Oral anti-infective drugs to treat the skin are described elsewhere (see Drugs for infections and infestations).
The final article covers sunscreens and sunblocks, which protect the skin against the damaging effects of the sun. Drug treatments for other specific disorders are discussed elsewhere (see Skin, hair, and nails).
For more information about the structure and function of the skin, see Growth and Repair.
Pain in the bones, muscles, or joints is a common problem. In many cases, it is due to a minor muscular injury, and drugs are used to relieve the pain while the problem gets better. More serious disorders may cause persistent pain or disability, and long-term medication is needed to control the symptoms.
The first two articles in this section cover nonsteroidal anti-inflammatory drugs and locally acting corticosteroids. These drugs can relieve symptoms of musculoskeletal disorders, such as inflammation and pain, but have no effect on the underlying causes.
Drugs used to treat specific joint and bone disorders are discussed in the next two articles. Antirheumatic drugs are commonly used to treat rheumatoid arthritis. They can slow or halt joint damage, thereby preventing the disability that may be the long-term result of this disorder. The next article covers drugs for bone disorders. These drugs prevent or halt the abnormal growth or breakdown of bone that occurs in bone disorders such as Paget’s disease and osteoporosis.
The final article in this section covers muscle relaxants, drugs that are used to relieve muscle spasms resulting from a variety of disorders.
For information on the structure and function of the musculoskeletal system, see Musculoskeletal System.
Disorders of the cardiovascular system are a major cause of poor health and early death in the developed world. In some cases, cardiovascular disorders can be improved by changes in lifestyle, such as improving diet or giving up smoking. In other cases, cardiovascular disorders require treatment with drugs that act on the blood vessels, the heart, or the kidneys.
The opening article in this section discusses drugs that are used to treat high blood pressure, a disorder that affects 1 in 5 people in developed countries. A number of these drugs are effective not only in lowering blood pressure but also in the treatment of heart failure, angina, and coronary artery disease.
The next article gives an overview of the types of drug that may be used in the treatment of arrhythmias, a group of disorders in which the heart beats extremely rapidly or with an abnormal rhythm.
Specific classes of drugs are discussed in separate articles. Beta-blockers and calcium channel blockers are used to treat certain arrhythmias; these drugs and nitrates also treat coronary artery disease; diuretics, ACE inhibitors, and beta-blockers are helpful in treating congestive heart failure; and most are useful in lowering high blood pressure.
Lipid-lowering drugs, which are used to reduce the risk of heart attack by lowering levels of fats in the blood, are discussed elsewhere (see Drugs acting on the endocrine system and metabolism).
For information on the structure and function of the cardiovascular system, see Cardiovascular System.
Improved understanding of blood and immune system disorders has led to advances in certain drug treatments. For example, there are now drugs that reduce the risk of heart attacks caused by blood clots. Recently developed drugs that act on the immune system also allow some forms of cancer to be controlled.
There are a number of potentially serious disorders that alter the clotting mechanism of the blood, resulting in either abnormal bleeding or the formation of unwanted clots. The first articles in this section describe the drugs that help to keep the clotting factors of the blood at normal levels.
The body’s immune system combats disease by activating white blood cells and proteins in the blood against infections and cancers. Sometimes, this system malfunctions and needs to be treated with drugs. Types of drug used to treat immune system malfunction include antiallergy drugs, which counter overreaction of the immune system; immunosuppressants, which prevent the immune system attacking the body’s own tissues; and interferon drugs, which boost immunity. Drugs for the immune deficiency disease AIDS are discussed elsewhere (see Drugs for HIV infection and AIDS). The final article in this section describes anticancer drugs, which can destroy cancerous cells or prevent them from spreading elsewhere in the body. The use of anticancer drugs is known as chemotherapy.
For more information on the structure and function of blood, see Blood and the Lymphatic and Immune Systems.
Conditions affecting the airways and lungs range from minor illnesses, such as the common cold, to long-term disorders, such asthma. The discomfort of coughs and colds may be eased with over-the-counter remedies. However, the symptoms of long-term disorders, such as shortness of breath, can be severe and require specific medical treatment.
This section describes some of the drugs used to treat both common illnesses, such as coughs and colds, and more serious conditions that affect the airways and lungs.
The first three articles in this section discuss drugs used to treat common symptoms of upper respiratory tract infections, such as nasal congestion, cough, and fever. The next article discusses bronchodilator drugs, which widen the airways of the lungs and are used to treat respiratory conditions in which breathing becomes difficult, such as asthma and chronic obstructive pulmonary disease. The final article in this section covers the use of corticosteroids in the treatment of respiratory conditions, including their use in preventing attacks of asthma. Drugs used for hay fever and other allergic disorders that affect the respiratory system are described elsewhere (see Antiallergy drugs), as are antibiotics used in the treatment of respiratory infections (see Drugs for infections and infestations).
For further information on the structure and function of the respiratory system, see Respiratory System.
Many of the drugs that act on the brain and nervous system relieve symptoms such as pain, insomnia, and anxiety. Others treat the disorders that cause the symptoms. As understanding of the chemical changes that occur in disorders such as depression improves, treatment is becoming more effective.
The opening article in this section describes groups of drugs known as painkillers. Most of these drugs work by preventing pain signals from being produced or altering the way in which the brain perceives pain. Drugs for migraine are covered next, followed by general anaesthetic drugs, which induce unconsciousness so that no pain can be felt during surgery. Local anaesthetic drugs, which block the transmission of pain signals in a specific body part, are then discussed.
The next articles in this section cover anticonvulsant drugs, sleeping drugs, and antianxiety drugs. Most work by reducing electrical activity in the brain to relieve symptoms but do not treat the underlying disorder.
Antidepressant drugs, which are described next, work by increasing levels of chemicals in the brain that regulate mood. Reduced levels of these chemicals can usually be found in people who are depressed.
In the final articles, antipsychotic drugs, mood-stabilizing drugs, and central nervous system stimulants are described. All of these drugs work by altering chemical activity in the brain.
For more information about the structure and function of the brain and nervous system, see Nervous System and Mental Function.
Eye and ear problems need prompt attention because they affect our most important senses. Many infections and chronic (long-term) conditions can be treated effectively with drugs. Medication for eye and ear disorders can often be administered easily as drops or ointments.
Most eye and ear disorders are minor and clear up rapidly with appropriate treatment. More serious and persistent problems may need medical attention and long-term use of drugs.
The first article in this section discusses drugs used to treat infections and inflammation of the eye. It also covers artificial tears, which relieve dry eyes, and mydriatics, a group of drugs that are used in the treatment of the inflammatory disorder uveitis.
Drugs that are used for glaucoma, a potentially serious condition if left untreated, are described in the next article. These drugs work in a variety of ways to relieve excess accumulation of fluid in the eye. As a result, the pressure that can damage the optic nerve is relieved, thereby diminishing the likelihood of partial or complete loss of vision.
The final article in this section discusses drugs used to treat disorders of the ear. These drugs range from treatments for bacterial infections and excess earwax to treatments for nausea and vomiting, symptoms that are commonly seen in inner ear disorders and can affect the balance mechanism. Drugs that relieve nausea and vomiting are discussed further elsewhere (see Antiemetic drugs).
Minor digestive problems, such as indigestion, constipation, or bouts of vomiting or diarrhoea, are common and short-lived, and most do not require treatment. However, drugs may sometimes be used to relieve digestive symptoms and treat specific disorders. Many of these drugs are available over the counter.
The first articles in this section discuss drugs that act on the upper digestive tract. These include antiemetics, which relieve nausea and vomiting; antacids, which relieve indigestion; and ulcer-healing drugs, which are used to treat peptic ulcers. Drugs that act on the lower digestive tract are described next. These include aminosalicylate drugs, which are used to treat long-term inflammation of the intestines; antidiarrhoeal drugs, which relieve diarrhoea; and laxatives, which are used to relieve constipation or to clear the intestine before a medical procedure. Antispasmodic drugs and motility stimulants, used to treat disorders caused by abnormal muscle action in the digestive tract, are discussed in the following article. The final article covers oral rehydration preparations, which replace water and other essential substances that are lost in vomiting and diarrhoea.
For information on the structure and function of the digestive system.
A well-balanced diet should contain adequate amounts of all vitamins and minerals required for health. For most people, supplements are unnecessary, and high doses may even be harmful. However, certain groups of people are vulnerable to vitamin or mineral deficiencies. Doctors may prescribe vitamin or mineral supplements for people in these groups to prevent a deficiency or to treat a deficiency that has already developed.
Groups who are particularly prone to developing vitamin and mineral deficiencies include young children, pregnant women, and elderly people, especially those who live alone. Those who are seriously ill due to injury or long-term illness, or those who have disorders that impair their ability to absorb nutrients from the digestive tract (see Malabsorption), are also at increased risk of deficiencies, not only of vitamins and minerals but also of other nutrients (see Nutritional deficiencies). These people may require dietary supplementation with extra proteins, carbohydrates, and fats as well as vitamins and minerals. In the case of individuals who are unable to eat and drink normally because of illness, such as a stroke, which prevents them from swallowing, nutrients sometimes have to be given in a liquid form by tube, either through the nose down to the stomach or directly into the stomach. More rarely, for example in people who have very severe intestinal disorders, nutrients may be administered directly into the bloodstream through a vein.
The body needs some nutrients, such as carbohydrates, proteins, and fats, in relatively large quantities but requires vitamins and minerals in only small amounts. The articles in this section describe the vitamins and minerals that doctors most commonly prescribe as dietary supplements. The first article deals with vitamins and the second with minerals.
Disorders of the endocrine system and metabolism, such as diabetes mellitus and hypothyroidism, may have wide-ranging, serious effects, and in some cases may be fatal if left untreated. Drug treatments can control the symptoms of these disorders and in many cases restore normal health to affected people.
The first article in this section covers corticosteroids, which are synthetic hormones that are chiefly used to treat inflammation in a variety of disorders and may also be used as hormone replacement therapy. The next four articles discuss drugs that control levels of insulin, thyroid hormones, and sex hormones in the body. Drugs that replace, inhibit, or stimulate some of the many hormones produced by the pituitary gland, which is the major hormone-secreting gland in the body, are covered next. The final article looks at lipid-lowering drugs, which control disorders in which the blood contains excessive levels of lipids (fats and related substances).
For more information on the endocrine system and metabolic disorders, see Diabetes Mellitus.
Advances in our understanding of how the reproductive and urinary systems function have led to improved drug treatments for conditions such as infertility and prostate disorders. Drugs can also prevent problems of the menopause or labour.
Drugs are used to increase the likelihood of conception if infertility is due to hormonal imbalances. These drugs are discussed in the first article of this section. The second article covers hormone replacement therapy, which helps to reduce the symptoms of the menopause, which occurs when levels of sex hormones decline.
The next article covers drugs for labour, which are most often used to prevent premature labour or to induce or hasten labour. They may also be used to prevent bleeding after delivery. In the following article, the various drug treatments for prostate disorders, including prostate cancer, are covered. The final article deals with drugs that affect bladder control. These drugs are used to treat urinary incontinence and retention.
Further information on drugs for the male and female reproductive and urinary systems, including articles on contraception and on the use of sex hormones and related drugs, can be found elsewhere. In addition, antibiotics are widely used to treat infections of the reproductive and urinary systems.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.