Povidone-iodine isn’t just a “brown antiseptic” from the operating room; today it is used to treat abrasions in the country, sterilize the skin before injections, gargle with SARS and even add it to cosmetic masks against inflammation.
Its versatility is explained by a unique complex of iodine with a polymer: the product kills bacteria, viruses and fungi, but almost does not sting and rarely causes allergies. Below we will analyze what povidone-iodine consists of, how it works and in what situations it really wins over other antiseptics.
What is povidone-iodine?
Composition and release form
Povidone-iodine is a complex of polyvinylpyrrolidone (PVP) and elemental iodine at a concentration of 100 mg/ml. PVP acts as a carrier sponge: it retains iodine and slowly releases it at the site of application, prolonging the antiseptic effect. The solution also includes glycerin, nonoxynol-9, citric acid and sodium buffer salts, which stabilize the pH and make the product less irritating to the skin and mucous membranes. The consistency of the drug is liquid, dark brown and has a characteristic odor of iodine.
Bottles of 30 ml (home first-aid kit), 100 ml (treatment rooms) and 1 liter (hospitals) are available on the market. The caps can be equipped with a pipette or a dispensing can, which is convenient when processing large areas. Thanks to the water base, the product is easy to dilute and wash off without leaving a sticky film.
Difference from regular iodine
An alcoholic solution of iodine releases the entire volume of the element at once, so it works quickly, but dries the skin a lot, stings and causes persistent staining. A complex with PVP reduces these side effects: the polymer releases iodine gradually, and therefore irritation is minimal, and the risk of tissue burns is lower.
Another difference is the change in color. In alcoholic iodine, the stain remains bright even after the alcohol evaporates, while in povidone-iodine, the paleness of the brown tint serves as a visual indicator: the iodine has been used up and it is necessary to repeat the treatment. This is convenient for long duty in the operating room or when dressing burns.
How does povidone-iodine work?
Mechanism of antiseptic action
Free iodine attacks thiol and hydroxyl groups of microbial cell proteins, denatures enzymes, and destroys cytoplasmic membranes. The first wave of death of bacteria, viruses and fungi occurs 15-30 seconds after contact with the solution, so it is often called a “rapid antiseptic”.
The PVP, meanwhile, remains on the surface as a “reservoir”. When active iodine is consumed, a new portion of the element is released from the polymer matrix, maintaining sterility for several hours. Due to such kinetics, the drug practically does not give an addictive effect – microorganisms do not have time to adapt.
What microorganisms is it effective against?
Povidone-iodine destroys gram-positive and gram-negative bacteria (including MRSA), inactivates viruses (including enveloped viruses – herpes, SARS-CoV-2), has a fungicidal and sporicidal effect, and also affects protozoa (amoebas, trichomonads).
It is important that activity is preserved in the presence of blood, serum and pus, where many other antiseptics “give up”. This quality makes the tool indispensable for primary surgical debridement and extensive injuries.
Main indications for use
Treatment of wounds and burns
For cuts, abrasions and burns, the solution can be poured directly onto the damaged surface or sprayed from a sterile spray. Dilution 1:2–1:20 reduces tissue staining and facilitates rinsing, but has almost no effect on the antimicrobial potential.
Povidone-iodine forms a thin film that does not interfere with skin respiration, so the epithelium underneath does not macerate. For II–IIIA degree burns, the product is combined with hydrogel dressings, which reduces pain and the risk of secondary infections.
Disinfection of the skin before surgery
Before inserting a catheter or making an incision, the skin is treated with an undiluted solution and allowed to dry naturally without wiping. For surgeons, a two-stage treatment of the hands is provided: two portions of 5 ml for 5 minutes each, paying attention to the subungual spaces.
This scheme provides both instant and prolonged destruction of flora: even if the glove is accidentally damaged, the number of microbes on the skin remains minimal.
Use in gynecology and urology
Before inserting an IUD or catheterization of the bladder, a 1:25 solution is used. It is gentle enough for the mucous membranes and does not disrupt the local microbiota as aggressively as alcohol antiseptics. In case of vulvovaginitis or prostatitis, sitz baths 1-2 times a day reduce swelling and itching, relieving symptoms.
Due to the low risk of developing resistance, povidone-iodine is often included in the protocols for debridement of the birth canal in preparation for cesarean section.
Instructions for use
How to apply the solution correctly
Dilute only with cold or warm (up to 37 °C) water: high temperature accelerates the decomposition of iodine and reduces efficiency. Applications are carried out with a sterile swab, starting from the center of the wound to the periphery, so as not to pull microbes inside.
In case of compresses, gauze is moistened with a solution of 1:5-1:10, applied for 20-30 minutes and covered with a loose bandage. If re-humidification is required, it is better to add a fresh solution rather than adding water – this way the concentration of active iodine will remain stable.
Frequency and duration of use
Usually, 2-3 procedures per day are enough. In case of bleeding wounds or profuse exudate, more frequent irrigation is allowed, but it is important to ensure that the daily volume does not exceed 50 ml of concentrated solution in an adult. When treating for more than 14 days on an area > 10% of the body, it is necessary to check the level of thyroid-stimulating hormone and free T4.
After the inflammation is reduced, switch to a one-time application before dressing: this accelerates epithelialization and saves the drug.
Features of use on mucous membranes
For the oral cavity and nasopharynx, a dilution of at least 1:100 is used to exclude chemical burns. Gargling lasts 30-60 seconds, after which the solution is spit out without drinking water. In gynecology and urology, the recommended concentration of 1:25 strikes a balance between efficiency and patient comfort.
If the mucous membrane has become whitish or severe dryness appears, this is a sign of an overdose: treatment is temporarily stopped and isotonic saline is switched to.
Contraindications and side effects
When not to use povidone-iodine
Absolute prohibitions include individual iodine intolerance, Hashimoto’s thyroiditis, nodular or endemic goiter, and Dühring’s dermatitis herpetiformis. The drug is not used in patients preparing for radioactive iodine therapy or scintigraphy: an excess of the element will distort the results of the examination.
Severe chronic renal failure is considered a relative contraindication, since iodine is excreted in the urine and can accumulate, provoking electrolyte shifts.
Possible allergic reactions
Most often, patients complain of a slight burning or darkening of the skin – this is a normal reaction to protein oxidation. Real allergic manifestations (urticaria, angioedema, bulillous dermatitis) are rare. At the first signs of hypersensitivity (itching, rash, erythema), the treatment is stopped and an alternative antiseptic is chosen.
To exclude unforeseen reactions, a test drop is carried out before the first use in sensitive patients: a small amount of the drug is applied to the wrist and observed for 15 minutes.
Effect on the thyroid gland with long-term use
Superficial application to large areas (> 10% of the body) for longer than two weeks can increase iodine absorption and provoke iodine-induced hyper- or hypothyroidism, especially in persons with latent thyroid pathology.
Doctors recommend monitoring TSH levels before therapy, 2 weeks and 1-3 months after withdrawal. If the indicators deviate, local antiseptics without iodine, such as octenidine or miramistin, are selected.
Povidone-iodine compared to other antiseptics
Povidone-iodine vs chlorhexidine
Chlorhexidine kills bacteria quickly and does not stain the skin, but its antiviral activity is limited and the spore form remains stable. Povidone-iodine covers the full spectrum, acts on biofilms, and is effective even at pH 2-7 and in the presence of organic matter. However, iodine can stain tissues and interact with metals, so when installing implants, priority is sometimes given to a colorless solution. Simultaneous application of two antiseptics reduces the activity of each and can cause irritation.
In practice, povidone-iodine is chosen for the primary treatment of contaminated wounds, and chlorhexidine is used for maintenance antiseptics on an outpatient basis.
When is it better to choose povidone-iodine
The drug is indispensable when the composition of the microflora is unknown or it is necessary to treat the mucous membrane (mouth, vagina). It is also preferred at the risk of viral infection (SARS, herpes) and in conditions where it is important to prevent the emergence of resistance, for example, in burn centers.
If you need an antiseptic for long-term daily treatment without staining (tattoo care, cosmetic procedures), it is more reasonable to use colorless chlorhexidine or octenidine.
Safety of use
Can it be used by children and pregnant women?
Newborns and infants under one year of age are prescribed povidone-iodine strictly for vital indications under the control of thyroid hormones, since their body is sensitive to excess iodine. In the first trimester of pregnancy, the drug is acceptable, but from the second trimester and during lactation, its use is contraindicated: iodine passes through the placenta, accumulates in the thyroid gland of the fetus and can cause neonatal hypothyroidism.
In emergency cases (for example, disinfection of field wounds), one-time use is acceptable, but it is better to postpone planned procedures or carry out alternative means.
How to store the drug and avoid overdose
The solution is stored at 15–25 °C away from direct light: ultraviolet accelerates the breakdown of iodine, and heating above 40 °C critically reduces efficiency. The bottle is kept strictly vertical and tightly closed so that the evaporation of water does not concentrate the solution.
In case of accidental ingestion, drink starch jelly or milk – they bind free iodine. In the hospital, 10 ml of 10% sodium thiosulfate is additionally administered intravenously every 3 hours until the symptoms of intoxication subside.
Answers to frequently asked questions
Can it be used for gargling?
Yes, but strictly in a low concentration (usually 2-3 drops per 200 ml of water). Rinsing lasts no more than a minute, then the solution is spit out. Course – up to 5 days in a row; Longer use requires monitoring of thyroid function. In case of a burning sensation, the solution is diluted additionally or switched to iodine-free antiseptics.
If a child under 6 years old does not know how to gargle without swallowing, it is better to limit himself to sprays based on miramistin.
How does povidone-iodine affect the skin with long-term use?
Surface staining is washed off with warm water and soap or a solution of sodium thiosulfate. With daily application, dryness is possible – it is eliminated with a mild cream with panthenol or lanolin. Blistering contact dermatitis occurs less than 1% of cases and is usually associated with individual intolerance rather than an “overdose” of iodine.
If the rash does not go away after 48 hours after stopping the drug, you should consult a dermatologist: a fungal or bacterial infection may have joined that requires specific treatment.
Literature:
- Povidone iodine in wound healing: A review of current concepts and practices (https://www.sciencedirect.com/science/article/pii/S1743919117305368#:~:text=Povidone%20iodine%2C%20the%20most%20commonly,its%20effect%20on%20excessive%20inflammation).
- Povidone Iodine: Properties, Mechanisms of Action, and Role in Infection Control and Staphylococcus aureus Decolonization (https://pmc.ncbi.nlm.nih.gov/articles/PMC7449185/)
- Povidone–iodine: use in hand disinfection, skin preparation and antiseptic irrigation (https://pmc.ncbi.nlm.nih.gov/articles/PMC7951395/)
Author: Natalia Kandybey, Candidate of Pharmaceutical Sciences, Quality Director of PJSC Pharmaceutical Factory “VIOLA”
