Tincture of iodine

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Iodine tincture
Various bottles of tincture of iodine from the former Soviet Union
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Formula I2

Tincture of iodine, iodine tincture, or weak iodine solution is an antiseptic. It is usually 2 to 3% elemental iodine, along with potassium iodide or sodium iodide, dissolved in a mixture of ethanol and water. Tincture solutions are characterized by the presence of alcohol. It was used from 1908 in pre-operative skin preparation by Italian surgeon Antonio Grossich. [1] [2]


In the United Kingdom, the development of an iodine solution for skin sterilisation was pioneered by Lionel Stretton. The British Medical Journal published the detail of his work at Kidderminster Infirmary in 1909. [3] Stretton used a much weaker solution than that used by Grossich. He claimed in 1915 that Grossich had been using a liquid akin to Liquor Iodi Fortis, and that it was he, Stretton, who had introduced the method using Tincture of Iodine BP which came to be used across the world. [4]

USP formulas

USP Tincture of Iodine is defined in the U.S. National Formulary (NF) as containing in each 100 mL, 1.8 to 2.2 grams of elemental iodine, and 2.1 to 2.6 grams of sodium iodide. Alcohol is 50 mL, and the balance is purified water. This "2% free iodine" solution has 0.08 mol/L of I2, which provides about 1 mg of free iodine per 0.05 mL drop. The "2% free iodine" description is based on the quantity of elemental iodine, not sodium/potassium iodide.[ citation needed ]

USP Strong Iodine Tincture is defined in the NF as containing in each 100 mL, 6.8 to 7.5 gram of iodine, and 4.7 to 5.5 gram of potassium iodide. Purified water is 50 mL and the balance is alcohol. This 7% tincture solution is about 3.5 times more concentrated than USP 2% tincture.[ citation needed ]

As in the case of Lugol's iodine, the role of iodide in the solution is to increase the solubility of the elemental iodine, by turning it to the soluble triiodide anion I3. However, since iodine has moderate solubility in ethanol, it is also assisted by this solvent directly. Lugol's iodine, by contrast, has no alcohol, and has twice the mass of potassium iodide as of elemental iodine. Alcohol content in the tincture of iodine can be determined by the methods of Alcock, Roscoe – Schorlemmer and Thurston – Thurston. [5]


As both USP solutions contain elemental iodine, which is moderately toxic when ingested in amounts larger than those required to disinfect water, tincture of iodine is sold labelled “for external use only,” and used primarily as a disinfectant.[ citation needed ]

Tincture of iodine is often found in emergency survival kits, used both to disinfect wounds and to sanitize surface water for drinking. When an alcohol solution is not desirable for this purpose, the alcohol-free Lugol's iodine, an aqueous solution of iodine in potassium iodide solution, or else povidone-iodine (brand names Wokadine, Betadine), a PVPI solution, can be used.

Small amounts may be added to suspect drinking water as a disinfectant (typically 5 mg free iodine per liter, or 5 drops of 2% tincture). Though this treatment is effective against bacteria and viruses, it does not protect against protozoan parasites such as Cryptosporidium and Giardia . [6]

Iodine solution is used to sanitize the surface of fruit and vegetables for bacteria and viruses. The common concentration for sanitization is 25 ppm iodophor for 1 minute. [7] However, the effectiveness depends on whether the solution penetrates into rifts, and whether dirt is effectively removed at first. The oocytes of protozoan parasites will not be killed, and it is also doubtful that bacterial spores will be killed. Iodine solutions should not be considered able to sanitize or disinfect salad, fruit or vegetables that are contaminated with feces. [8]

Iodine tincture is not a recommended source of solely-nutritional iodine. Nutritional iodine is better supplied in the form of the less toxic iodide (see SSKI) or iodate salts, which the body can easily convert to thyroid hormone.

Nevertheless, the iodide in tincture of iodine used as a water disinfectant does supply more than adequate nutritional iodine, perhaps 30 or more times the recommended daily allowance per liter or quart. Application of tincture or Lugol's to the skin also results in absorption and bioavailability of some moderate fraction of the iodine. This method can be used to saturate the thyroid with iodine to help prevent the excessive uptake of radioactive iodine-131 in a nuclear accident. [9]

See also

Related Research Articles

A bactericide or bacteriocide, sometimes abbreviated Bcidal, is a substance which kills bacteria. Bactericides are disinfectants, antiseptics, or antibiotics. However, material surfaces can also have bactericidal properties based solely on their physical surface structure, as for example biomaterials like insect wings.

<span class="mw-page-title-main">Iodine</span> Chemical element, symbol I and atomic number 53

Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at 114 °C (237 °F), and boils to a violet gas at 184 °C (363 °F). The element was discovered by the French chemist Bernard Courtois in 1811 and was named two years later by Joseph Louis Gay-Lussac, after the Ancient Greek Ιώδης 'violet-coloured'.

An antiseptic is an antimicrobial substance or compound that is applied to living tissue to reduce the possibility of sepsis, infection or putrefaction. Antiseptics are generally distinguished from antibiotics by the latter's ability to safely destroy bacteria within the body, and from disinfectants, which destroy microorganisms found on non-living objects.

<span class="mw-page-title-main">Sodium hypochlorite</span> Chemical compound (known in solution as bleach)

Sodium hypochlorite, commonly known in a dilute solution as (chlorine) bleach, is an inorganic chemical compound with the formula NaOCl, consisting of a sodium cation and a hypochlorite anion. It may also be viewed as the sodium salt of hypochlorous acid. The anhydrous compound is unstable and may decompose explosively. It can be crystallized as a pentahydrate NaOCl·5H
, a pale greenish-yellow solid which is not explosive and is stable if kept refrigerated.

<span class="mw-page-title-main">Chlorine dioxide</span> Chemical compound

Chlorine dioxide is a chemical compound with the formula ClO2 that exists as yellowish-green gas above 11 °C, a reddish-brown liquid between 11 °C and −59 °C, and as bright orange crystals below −59 °C. It is usually handled as an aqueous solution. It is commonly used as a bleach. More recent developments have extended its applications in food processing and as a disinfectant.

<span class="mw-page-title-main">Disinfectant</span> Antimicrobial agent that inactivates or destroys microbes

A disinfectant is a chemical substance or compound used to inactivate or destroy microorganisms on inert surfaces. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, which is an extreme physical or chemical process that kills all types of life. Disinfectants are generally distinguished from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. Disinfectants are also different from biocides—the latter are intended to destroy all forms of life, not just microorganisms. Disinfectants work by destroying the cell wall of microbes or interfering with their metabolism. It is also a form of decontamination, and can be defined as the process whereby physical or chemical methods are used to reduce the amount of pathogenic microorganisms on a surface.

ATC code D08Antiseptics and disinfectants is a therapeutic subgroup of the Anatomical Therapeutic Chemical Classification System, a system of alphanumeric codes developed by the World Health Organization (WHO) for the classification of drugs and other medical products. Subgroup D08 is part of the anatomical group D Dermatologicals.

<span class="mw-page-title-main">Chlorhexidine</span> Disinfectant and antiseptic

Chlorhexidine is a disinfectant and antiseptic with the molecular formula C22H30Cl2N10, which is used for skin disinfection before surgery and to sterilize surgical instruments. It is also used for cleaning wounds, preventing dental plaque, treating yeast infections of the mouth, and to keep urinary catheters from blocking. It is used as a liquid or a powder. It is known by the salt forms: chlorhexidine gluconate (chlorhexidine digluconate) and chlorhexidine acetate (chlorhexidine diacetate).

<span class="mw-page-title-main">Potassium iodide</span> Ionic compound (KI)

Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are used. In the third world it is also used for treating skin sporotrichosis and phycomycosis. It is a supplement used by people with low dietary intake of iodine. It is administered orally.

<span class="mw-page-title-main">Lugol's iodine</span> Aqueous solution of iodine and potassium iodide

Lugol's iodine, also known as aqueous iodine and strong iodine solution, is a solution of potassium iodide with iodine in water. It is a medication and disinfectant used for a number of purposes. Taken by mouth it is used to treat thyrotoxicosis until surgery can be carried out, protect the thyroid gland from radioactive iodine, and to treat iodine deficiency. When applied to the cervix it is used to help in screening for cervical cancer. As a disinfectant it may be applied to small wounds such as a needle stick injury. A small amount may also be used for emergency disinfection of drinking water.

<span class="mw-page-title-main">Povidone-iodine</span> Antiseptic solution

Povidone-iodine (PVP-I), also known as iodopovidone, is an antiseptic used for skin disinfection before and after surgery. It may be used both to disinfect the hands of healthcare providers and the skin of the person they are caring for. It may also be used for minor wounds. It may be applied to the skin as a liquid or a powder.

An iodophor is a preparation containing iodine complexed with a solubilizing agent, such as a surfactant or water-soluble polymers, for example, povidone. The result is a water-soluble material that releases free iodine when in solution. Iodophors are prepared by mixing iodine with the solubilizing agent; heat can be used to speed up the reaction.

<span class="mw-page-title-main">Melzer's reagent</span>

Melzer's reagent is a chemical reagent used by mycologists to assist with the identification of fungi, and by phytopathologists for fungi that are plant pathogens.

Cadexomer iodine is an iodophor that is produced by the reaction of dextrin with epichlorhydrin coupled with ion-exchange groups and iodine. It is a water-soluble modified starch polymer containing 0.9% iodine, calculated on a weight-weight basis, within a helical matrix.

<span class="mw-page-title-main">Bleach</span> Chemicals used to whiten or disinfect

Bleach is the generic name for any chemical product that is used industrially or domestically to remove colour (whitening) from fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically to a dilute solution of sodium hypochlorite, also called "liquid bleach".

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Potassium hypochlorite is the potassium salt of hypochlorous acid. It is used in variable concentrations, often diluted in water solution. It has a light grey color and a strong chlorine smell. It can be used as a disinfectant.

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<span class="mw-page-title-main">Iodine (medical use)</span> Topical antiseptic and supplement

Iodine is used to treat and prevent iodine deficiency and as an antiseptic. For iodine deficiency it can be given by mouth or injection into a muscle. As an antiseptic it may be used on wounds that are wet or to disinfect the skin before surgery.


  1. Block SS (2001). Disinfection, Sterilization, and Preservation, 5e. Lippincott Williams & Wilkins. p. 922. ISBN   978-0-683-30740-5 . Retrieved 7 January 2013.
  2. Barenfanger J, Drake C, Lawhorn J, Verhulst SJ (May 2004). "Comparison of chlorhexidine and tincture of iodine for skin antisepsis in preparation for blood sample collection". Journal of Clinical Microbiology. 42 (5): 2216–7. doi:10.1128/JCM.42.5.2216-2217.2004. PMC   404630 . PMID   15131193.
  3. Stretton JL (August 1909). "The Sterilization of the Skin of Operation Areas". British Medical Journal. 2 (2537): 368–9. doi:10.1136/bmj.2.2537.368-a. PMC   2320536 . PMID   20764617.
  4. Stretton JL (May 1915). "The Sterilisation of the Skin with Tincture of Iodine". British Medical Journal. 1 (2838): 886–7. doi:10.1136/bmj.1.2838.886. PMC   2302255 . PMID   20767647.
  5. Thurston A, Thurston A (1912). "Determination of alcohol in tincture of iodine". Journal of the American Pharmaceutical Association. 1 (10): 1155. doi:10.1002/jps.3080011017.
  6. "A Guide to Drinking Water Treatment and Sanitation for Backcountry & Travel Use". Centers for Disease Control and Prevention. Retrieved 14 February 2015.
  7. "Sanitizers and Disinfectants: The Chemicals of Prevention, Foodsafety Magazine". Food Safety Magazine. Retrieved 14 February 2015.
  8. "Surface decontamination of fruit and vegetable eaten raw". World Health Organization. 1998. Retrieved 14 February 2015.
  9. "Tincture of iodine keeps radiation away". Science News. 1985. Retrieved 12 June 2021.