A
therapeutic effect is a consequence of a medical treatment of any kind, the results of which are judged to be desirable and beneficial. This is true whether the result was expected, unexpected, or even an
unintended consequenceUnintended consequences are outcomes that are not the results originally intended by a particular action. The unintended results may be foreseen or unforeseen, but they should be the logical or likely results of the action...
of the treatment. An
adverse effectIn medicine, an adverse effect is a harmful and undesired effect resulting from a medication or other intervention such as surgery. An adverse effect may be termed a "side effect", when judged to be secondary to a main or therapeutic effect, and may result from an unsuitable or incorrect dosage or...
, on the other hand, is a harmful and undesired effect.
What constitutes a therapeutic effect versus a side effect is a matter of both the nature of the situation in which a treatment is used and the goals of treatment. There is no inherent difference between therapeutic and undesired side effects; both responses are behavioral/physiologic changes which occur as a response to the treatment strategy or agent. However, those changes which are viewed as desirable, given the situation, are called therapeutic; those undesirable for the situation are viewed as unfavorable.
Scope of treatments
Many people think of therapeutic and undesired side effects as only applying to
medicationA pharmaceutical drug, also referred to as medicine, medication or medicament, can be loosely defined as any chemical substance intended for use in the medical diagnosis, cure, treatment, or prevention of disease.- Classification :...
s,
drugA drug, broadly speaking, is any substance that, when absorbed into the body of a living organism, alters normal bodily function. There is no single, precise definition, as there are different meanings in drug control law, government regulations, medicine, and colloquial usage.In pharmacology, a...
s or
supplementSupplement may refer to:* Dietary supplement* Bodybuilding supplement* Supplement, one of a pair of supplementary angles, considered relative to the other* Supplement * A role-playing or tabletop game supplement, see expansion pack...
s, perhaps because
pharmacologyPharmacology is the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function. If substances have medicinal properties, they are considered pharmaceuticals...
approaches are more often more rigorously evaluated by comparison with
placeboA placebo is a sham medical intervention. In one common placebo procedure, a patient is given an inert sugar pill, told that it may improve his/her condition, but not told that it is in fact inert...
treatments, but this is not the case. It applies to any treatment approach, including
surgerySurgery is a medical specialty that uses operative manual and instrumental techniques on a patient to investigate and/or treat a pathological condition such as disease or injury, to help improve bodily function or appearance, or sometimes for some other reason...
,
physical therapyPhysical therapy is a health care profession which provides services to individuals in order to develop, maintain and restore maximum movement and functional ability throughout life...
,
psychotherapyPsychotherapy or personal counseling with a psychotherapist, is an intentional interpersonal relationship used by trained psychotherapists to aid a client or patient in problems of living.It aims to increase the individual's sense of their own well-being...
, treatment with compounds,
faith healingFaith healing is a concept that religious belief can bring about healing—either through prayers or rituals that, according to adherents, evoke a divine presence and power toward correcting disease and disability in particular indicated individuals. Belief in divine intervention in illness or...
,
hypnosisHypnosis is a mental state or set of attitudes usually induced by a procedure known as a hypnotic induction, which is commonly composed of a series of preliminary instructions and suggestions. Hypnotic suggestions may be delivered by a hypnotist in the presence of the subject, or may be...
, holistic methods, etc.; any method of which one can conceive.
The administration of a compound was selected for the pharmacologic example below because this form of treatment is more readily checked with the comparative treatment versus the placebo approach designed so that people are often unable to recognized the difference, at least at a conscious or group awareness level. Other therapeutic methods are typically more difficult to test because the test subjects can more easily recognize the key aspect of treatment which is being tested; it thus becomes far more difficult to apply the placebo control methodology. The
placebo effectPlacebo effect may refer to:* Placebo effect, the tendency of any medication or treatment, even an inert or ineffective one, to exhibit results simply because the recipient believes that it will work...
is always relevant in all treatments; behavior and symptoms do change, however the presumed mechanism may primarily be the power of the mind which controls behavior and perception all the time, and the fact that if an individual believes that their situation will change then their situation actually does change.
To maximize the therapeutic effects and minimize the side effects of any treatment, recognition and quantification of the situation, in multiple dimensions, is a critical prerequisite. There are many situations in which the effects of a treatment, both those often viewed as both desirable and undesirable can be used in combination with other treatments in a complex strategy so that, for the individual being treated, the best end results actually depend on side effects contributing to the overall therapeutic benefit. Achieving this reflects a higher degree of physician and patient interactive relationship, trust, sophistication and skill. The same principles applies to all agents, including what most people view as simply food, water, air and oxygen. Situation, timing and great familiarity of the multiple usual responses to agents is critically important for wisely selecting all treatments. Maintaining and improving health strongly depends on promoting desirable effects while lessening the impact of undesirable effects of many interacting issues. However, the number of interacting issues, powerfully influenced by internal individual control mechanisms, make understanding and knowing all the issues a mind-boggling complex task which, at least in this day and age, is never totally understandable. There are simply too many complex interacting issues, never totally knowable, definable and predictable.
Pharmacology example
For example, it widely promoted that "natural" or "organic" agents are more healthy. However, everything in the world has multiple and varying responses when used; both desirable and undesirable effects are inherent parts of the total response. Even
waterWater is an ubiquitous chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life.In typical usage, water refers only to its liquid form or state, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam. Water covers 71%...
– on which all life on earth depends – can have undesirable, even fatal effects; while increased intake of water can save a
dehydratedDehydration is defined as excessive loss of body water. It is literally the removal of water from an object. In physiological terms, it entails a relative deficiency of water molecules in relation to other dissolved solutes...
patient, too much water can lead to
water intoxicationWater intoxication is a potentially fatal disturbance in brain functions that results when the normal balance of electrolytes in the body is pushed outside of safe limits by over-consumption of water.Normal, healthy individuals have little reason to worry about accidentally consuming too...
, sometimes resulting in death, such as in severe
pulmonary edemaPulmonary edema , or oedema , is fluid accumulation in the lungs. It leads to impaired gas exchange and may cause respiratory failure. It is due to either failure of the heart to remove fluid from the lung circulation or a direct injury to the lung parenchyma...
.
As a simple example, the therapeutic effect of
diphenhydramineDiphenhydramine hydrochloride is a chemical mainly used as an antihistamine, antiemetic, sedative, and hypnotic. It is produced and marketed under the trade name Benadryl by McNeil-PPC in the U.S. and Canada, and Dimedrol in other countries...
, when used for
nasal congestionNasal congestion is the blockage of the nasal passages usually due to membranes lining the nose becoming swollen from inflamed blood vessels. It is also known as nasal blockage, nasal obstruction, blocked nose, runny nose, stuffy nose, or stuffed up nose.Nasal congestion has many causes and can...
, is to lessen
mucous membraneThe mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line various body cavities that are exposed to the external environment and internal organs. It is at several places continuous with skin: at the nostrils, the...
secretions and the side effect is drowsiness. However, when used for
insomniaInsomnia is a symptom of any of several sleep disorders, characterized by persistent difficulty falling asleep or staying asleep despite the opportunity. Insomnia is a symptom, not a stand-alone diagnosis or a disease. By definition, insomnia is "difficulty initiating or maintaining sleep, or both"...
, as in many over-the-counter preparations, the therapeutic effect of diphenhydramine is drowsiness and the side effect is mucous membrane dryness, which is undesirable, especially if the person using the agent for sleep is already suffering from dry membranes. The more important issue is not the agent, but the situation in which the therapeutic agent is used; a change in the situation can easily totally reverse what is usually considered a therapeutic versus an undesirable side effect.
Diphenhydramine was originally marketed under the brand name Benadryl in the early 1950s. When taken orally, it typically induces two behavioral responses: (1) drying of
mucous membraneThe mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion. They line various body cavities that are exposed to the external environment and internal organs. It is at several places continuous with skin: at the nostrils, the...
s, potentially helpful in cases of increased nasal congestion and (2) drowsiness. Diphenhydramine was promoted for reducing nasal congestion, thus response 1 was the considered the therapeutic effect. Since response 2, the drowsiness response, was typically not viewed as desirable, drowsiness was termed a side effect.
When diphenhydramine is used as treatment, these two effects, individual responses, are always bound together and cannot be separated. Even though the
doseA dose is a quantity of something that may impact an organism biologically; the greater the quantity, the larger the dose. In nutrition, the term is usually applied to how much of a specific nutrient is in a person's diet or in a particular food, meal, or dietary supplement...
can be changed and the relative degree of the two responses may be reduced or increased and the degree of the two different responses may be somewhat different at different doses, the two responses cannot be separated. For simplicity of illustration, only two typical responses are mentioned. For completeness, be aware that as with most treatments people usually exhibit additional behavioral responses to diphenhydramine beyond the two mentioned.
http://www.nlm.nih.gov/medlineplus/druginfo/meds/a682539.html
Reducing complexity
The desire to simplify clinical situations and variables is one of the important reasons that physicians often prefer highly refined and regulated
prescription drugA prescription drug is a licensed medicine that is regulated by legislation to require a prescription before it can be obtained. The term is used to distinguish it from over-the-counter drugs which can be obtained without a prescription...
preparations, as opposed to less refined and regulated products, often marketed as "natural" to imply safety.
Products from nature are essentially always complex mixtures of large numbers of different chemical agents, many only partially understood in term of usual desirable and undesirable responses, relationships of these effects to specific doses and with varying amounts of dose present within any given sample available.
The pharmaceutical industry highly purifies, concentrates and sometimes makes very controlled modifications of agents obtained from natural sources, when there is no alternative source, so as to select out and greatly reduce the variables in the treatment agent offered. Ratios of relative responses, often summarized using the concept
therapeutic indexThe therapeutic index , is a comparison of the amount of a therapeutic agent that causes the therapeutic effect to the amount that causes death. Quantitatively, it is the ratio given by the lethal dose divided by the therapeutic dose...
, are utilized to help understand and communicate treatment responses.
A pharmaceutical grade agent does not make the patient any more simple but it does greatly simplify, narrow and make more definable and predictable both the usual desirable and undesirable effects of the treatment agent, based on careful tracking of the responses of many individuals who have taken the agent, in widely varying amounts and situations, in the past. This purification can greatly improve the probability for both the patient and the physician that the resulting responses to the treatment are likely to be more predictable and controllable.