Rubbing alcohol, USP / B.P. is a liquid prepared and used primarily for topical application. It is prepared from a special denatured alcohol solution and contains 97.5-100% by volume of pure, concentrated ethanol (ethyl alcohol) or isopropyl alcohol (isopropanol).[1] Individual manufacturers can use their own "formulation standards" in which the ethanol content usually ranges from 70-99% v/v.[2] In the UK the equivalent skin preparation is surgical spirit which is always an ethyl alcohol-isopropyl alcohol mixture.
The term "rubbing alcohol" has become a general non-specific term for either isopropyl alcohol (isopropanol) or ethyl alcohol (ethanol) rubbing-alcohol products.
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Rubbing alcohol is a cellular, volatile, and flammable liquid. It is transparent, though it can be coloured as desired. It has an extremely bitter taste from its additives and (in the absence of added odorous substances) a characteristic odor. The specific gravity of Formula 23-H is between 0.8691 and 0.8771 at 15.56°.
Isopropyl rubbing alcohol USP/B.P. contains 68–99% of isopropanol (isopropyl alcohol) by volume, the remainder consisting of water, with or without color additives, suitable stabilizers, and perfume oils. Isopropyl alcohol is oxidized by the liver into acetone.[3] Symptoms of isopropyl alcohol poisoning include flushing, headache, dizziness, central nervous system depression, nausea, vomiting, anesthesia, and coma.[3]
Rubbing alcohol can be applied as a cooling, soothing application for bedridden patients and athletes. It is also widely used for cleansing surgeons' hands and instruments and for the disinfection of skin prior to penetration by a hypodermic needle. As an antiseptic it is good against vegetative bacteria and fair against fungi and viruses, but is ineffective against spores. Welders also use rubbing alcohol to clean welding surfaces before welding. This removes oils and impurities on the surface. It is widely believed that 99% isopropyl alcohol provides the greatest reduction in bacterial count; however, this is incorrect as there does not appear to be significant differences beyond a 60% concentration.[2] Rubbing alcohol is also a feeble anesthetic and a mild counterirritant. It is not drinkable, although people have been known to attempt ingestion.[3]
Rubbing alcohol is recognized as a rubefacient because it evaporates quickly and is used to cool and soothe skin. It is, however, more widely used as an antiseptic for disinfecting surfaces or cleaning minor cuts or abrasions.[2]
Isopropyl rubbing alcohol can also be supplied in a 99% concentration. This product can also be used to harden skin, such as in the case of the feet of novice hikers, or the fingertips of guitarists. Care should always be taken, and the label should be read carefully.[4]
In the United States, rubbing alcohol, USP and all preparations coming under the classification of Rubbing Alcohols must be manufactured in accordance with the requirements of the US Treasury Department, Bureau of Alcohol, Tobacco, and Firearms, using Formula 23-H (8 parts by volume of acetone, 1.5 parts by volume of methyl isobutyl ketone, and 100 parts by volume of ethyl alcohol). It contains 97.5-100% by volume of absolute ethyl alcohol, the rest consists of water and the denaturants, with or without color additives, and perfume oils. Rubbing Alcohol contains in each 100 mL not less than 355 mg of sucrose octaacetate or not less than 1.40 mg of denatonium benzoate. The preparation may be colored with one or more color additives. A suitable stabilizer may also be added.[6]
Product labels for rubbing alcohol include a number of warnings about the chemical, including the flammability hazards and its intended use only as a topical antiseptic and not for internal wounds or consumption. It should be used in a well-ventilated area due to inhalation hazards. Poisoning can occur from ingestion, inhalation, or consumption of rubbing alcohol.[7][8]