In United States safety standards, precautionary statements are sentences providing information on potential hazards, and proper procedures. They are used in situations from consumer product on labels and manuals, to descriptions of physical activities. Various methods are used to bring focus to them, such as setting apart from normal text, graphic icons, changes in text's font and color. Texts will often clarify the types of statements and their meanings within the text. Common precautionary statements are described below.

In 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 procedure, which could be due to medical error. Adverse effects are sometimes referred to as "iatrogenic" because they are generated by a physician/treatment. Some adverse effects only occur only when starting, increasing or discontinuing a treatment. Using a drug or other medical intervention which is contraindicated may increase the risk of adverse effects. Adverse effects may cause medical complications of a disease or procedure and negatively affect its prognosis. They may also lead to non-compliance with a treatment regimen. The harmful outcome is usually indicated by some result such as morbidity, mortality, alteration in body weight, levels of enzymes, loss of function, or as a pathological change detected at the microscopic, macroscopic or physiological level. It may also be indicated by symptoms reported by a patient. Adverse effects may cause a reversible or irreversible change, including an increase or decrease in the susceptibility of the individual to other chemicals, foods, or procedures, such as drug interactions. In clinical trials, a distinction is made between adverse events (AEs) and serious adverse events (SAEs). Generally, any event which causes death, permanent damage, birth defects, or requires hospitalization is considered an SAE.[1] The results of these trials are often included in the labeling of the medication to provide information both for patients and the prescribing physicians.

Packaging is the science, art and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of design, evaluation, and production of packages. Packaging can be described as a coordinated system of preparing goods for transport, warehousing, logistics, sale, and end use. Packaging contains, protects, preserves, transports, informs, and sells.[1] In many countries it is fully integrated into government, business, institutional, industrial, and personal use.

A contraindication (pronounced as contra-indication) is a condition or factor that speaks against a certain measure. It is mostly used in medicine, with regard to factors that increase the risks involved in using a particular drug, carrying out a medical procedure, or engaging in a particular activity. Some contraindications are absolute, meaning that there are no reasonable circumstances for undertaking a course of action. For example, a baby with a fever should never be given aspirin because of the risk of Reye's syndrome, and a person with an anaphylactic food allergy should never eat the food to which they are allergic. Similarly, a person with hemochromatosis should not be administered iron preparations. Other contraindications are relative, meaning that the patient is at higher risk of complications, but that these risks may be outweighed by other considerations or mitigated by other measures. For example, a pregnant woman should normally avoid getting X-rays, but the risk may be far less than the risk of not diagnosing or being able to treat a serious condition such as tuberculosis or a broken bone. Relative contraindications may also be referred to as cautions, such as in the British National Formulary.

An intraocular lens (IOL) is an implanted lens in the eye, usually replacing the existing crystalline lens because it has been clouded over by a cataract, or as a form of refractive surgery to change the eye's optical power. It usually consists of a small plastic lens with plastic side struts, called haptics, to hold the lens in place within the capsular bag inside the eye.[citation needed] IOLs were traditionally made of an inflexible material (PMMA), although this has largely been superseded by the use of flexible materials. Most IOLs fitted today are fixed monofocal lenses matched to distance vision. However, other types are available, such as multifocal IOLs which provide the patient with multiple-focused vision at far and reading distance, and adaptive IOLs which provide the patient with limited visual accommodation.

"a manual usually accompanying a technical device and explaining how to install or operate it" Essential Requirements - Medical Device Directive 93/42/EEC - Annex I, 13.1: Each device must be accompanied by the information needed to use it safely and to identify the manufacturer, taking account of the training and knowledge of the potential user. This information comprises the details on the label and the data in the instructions for use. As far as practicable and appropriate, the information needed to use the device safely must be set out on the device itself and/or on the packaging of each unit. If not practicable, the information must be set out in the leaflet supplied with one or more devices. Instructions for use must be included in the packaging for every device. By way of exception, no such instruction leaflet is needed for devices in Class I or Class IIa if they can be used completely safely without any such instructions.