Adverse effect

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An adverse effect is an undesired harmful effect resulting from a

In terms of drugs, adverse events may be defined as: "Any untoward medical occurrence in a patient or clinical investigation subject administered a pharmaceutical product and which does not necessarily have to have a causal relationship with this treatment."[3]

In clinical trials, a is made between an

The term "life-threatening" in the context of a serious adverse event refers to an event in which the patient was at risk of death at the time of the event; it does not refer to an event which hypothetically might have caused death if it were more severe.[3]

Reporting systems

In many countries, adverse effects are required by law to be reported, researched in clinical trials and included into the patient information accompanying medical devices and drugs for sale to the public. Investigators in human clinical trials are obligated to report these events in clinical study reports.^[5] Research suggests that these events are often inadequately reported in publicly available reports.^[6] Because of the lack of these data and uncertainty about methods for synthesising them, individuals conducting systematic reviews and meta-analyses of therapeutic interventions often unknowingly overemphasise health benefit.^[7] To balance the overemphasis on benefit, scholars have called for more complete reporting of harm from clinical trials.^[8]

United Kingdom

The

Adverse reaction reporting is an important component of New Zealand's pharmacovigilance activities. The Centre for Adverse Reactions Monitoring (CARM) in Dunedin is New Zealand's national monitoring centre for adverse reactions. It collects and evaluates spontaneous reports of adverse reactions to medicines, vaccines, herbal products and dietary supplements from health professionals in New Zealand. Currently the CARM database holds over 80,000 reports and provides New Zealand-specific information on adverse reactions to these products, and serves to support clinical decision making when unusual symptoms are thought to be therapy related

Canada

In Canada, adverse reaction reporting is an important component of the surveillance of marketed health products conducted by the Health Products and Food Branch (HPFB) of Health Canada. Within HPFB, the Marketed Health Products Directorate leads the coordination and implementation of consistent monitoring practices with regards to assessment of signals and safety trends, and risk communications concerning regulated marketed health products.

MHPD also works closely with international organizations to facilitate the sharing of information. Adverse reaction reporting is mandatory for the industry and voluntary for consumers and health professionals.

Limitations

In principle, medical professionals are required to report all adverse effects related to a specific form of therapy. In practice, it is at the discretion of the professional to determine whether a medical event is at all related to the therapy. As a result, routine adverse effects reporting often may not include long-term and subtle effects that may ultimately be attributed to a therapy.^[9]

Part of the difficulty is identifying the source of a complaint. A headache in a patient taking medication for influenza may be caused by the underlying disease or may be an adverse effect of the treatment. In patients with end-stage cancer, death is a very likely outcome and whether the drug is the cause or a bystander is often difficult to discern.^{[citation needed]}

By situation

Medical procedures

Other nonsurgical physical procedures, such as high-intensity radiation therapy, may cause burns and alterations in the skin. In general, these therapies try to avoid damage to healthy tissues while maximizing the therapeutic effect.

Adverse effects can occur as a collateral or side effect of many interventions, but they are particularly important in

Most drugs have a large list of nonsevere or mild adverse effects which do not rule out continued usage. These effects, which have a widely variable incidence according to individual sensitivity, include nausea, dizziness, diarrhea, malaise, vomiting, headache, dermatitis, dry mouth, etc. These can be considered a form of pseudo-allergic reaction, as not all users experience these effects; many users experience none at all.

The Medication Appropriateness Tool for Comorbid Health Conditions in Dementia

• Abortion, miscarriage or uterine hemorrhage associated with misoprostol (Cytotec), a labor-inducing drug (this is a case where the adverse effect has been used legally and illegally for performing abortions)^[12]
• Addiction to many sedatives and analgesics, such as diazepam, morphine, etc.^[13]
• Birth defects associated with thalidomide
• intestine associated with aspirin therapy^[14]
• COX-2 inhibitors (i.e. Vioxx)^[15]
• kidney failure associated with gentamicin (an antibiotic)^[16]
• Death, following sedation, in children using propofol (Diprivan)^[17]
• Depression or hepatic injury caused by interferon^[18]
• Diabetes caused by atypical antipsychotic medications (neuroleptic psychiatric drugs)^[19]
• Diarrhea caused by the use of orlistat (Xenical)^[20]
• Erectile dysfunction associated with many drugs, such as antidepressants^[21]
• Fever associated with vaccination^[22][23]
• Glaucoma associated with corticosteroid-based eye drops^[24]
• Hair loss and anemia may be caused by chemotherapy against cancer, leukemia, etc.^[25]
• Headache following spinal anaesthesia^[26]
• Hypertension in ephedrine users, which prompted FDA to remove the dietary supplement status of ephedra extracts^[27]
• Insomnia caused by stimulants, methylphenidate (Ritalin), Adderall, etc.^[28]
• Lactic acidosis associated with the use of stavudine (Zerit, for HIV therapy)^[29] or metformin (for diabetes)^[30]
• Mania caused by corticosteroids^[31]
• Liver damage from paracetamol^[32]
• Melasma and thrombosis associated with use of estrogen-containing hormonal contraception, such as the combined oral contraceptive pill^[33][34]
• Priapism associated with the use of sildenafil^[35]
• Rhabdomyolysis associated with statins (anticholesterol drugs)^[36]
• Seizures caused by withdrawal from benzodiazepines^[37]
• antihistamine use. Some antihistamines are used in sleep aids explicitly because they cause drowsiness.^[38]
• Stroke or heart attack associated with sildenafil (Viagra), when used with nitroglycerin
• Suicide, increased tendency associated to the use of fluoxetine and other selective serotonin reuptake inhibitor (SSRI) antidepressants
• Tardive dyskinesia associated with use of metoclopramide and many antipsychotic medications^[39]

Controversies

Sometimes, putative medical adverse effects are regarded as controversial and generate heated discussions in society and lawsuits against drug manufacturers. One example is the recent controversy as to whether autism was linked to the MMR vaccine (or to thiomersal, a mercury-based preservative used in some vaccines). No link has been found in several large studies, and despite removal of thimerosal from most early childhood vaccines beginning with those manufactured in 2003, the rate of autism has not decreased as would be expected if it had been the causative agent.^[40][41]

Another instance is the potential adverse effects of silicone breast implants, which led to class actions brought by tens of thousands of plaintiffs against manufacturers of gel-based implants, due to allegations of damage to the immune system which have not yet been conclusively proven.^[42] In 1998, Dow Corning settled its remaining suits for $3.2 Billion and went into bankruptcy.^[43]

Due to the exceedingly high impact on public health of widely used medications, such as

References