How to Make a 0.5% Povidone-Iodine Solution

December 12, 2025 •

4 min read

According to scientific studies, diluted povidone-iodine can be more effective against certain microorganisms than the standard 10% concentration. Learn how to make a 0.5% povidone-iodine solution safely and accurately for use as a topical antiseptic. Always consult a healthcare professional before use.

Quick Summary

This guide provides instructions and calculations for safely diluting a 10% povidone-iodine concentrate to a 0.5% solution. It details necessary equipment, preparation steps, and crucial safety measures to follow during the process.

Key Points

Start with 10% concentrate: This guide assumes a starting material of standard 10% povidone-iodine solution.
Accurate measurement is crucial: A graduated cylinder or syringe is required for precise volume measurements to achieve the correct 0.5% dilution.
Calculate dilution ratio: Use the formula (C1)(V1) = (C2)(V2) to determine the correct volumes of concentrate and diluent for your desired final volume.
Use sterile water only: Tap water can introduce contaminants that affect the solution's purity and efficacy, especially for medical uses.
Wear safety gear: Protect your skin and eyes by wearing gloves and safety goggles while handling and mixing povidone-iodine.
Label and store correctly: Use a dark, airtight container and clearly label it with the concentration and date to ensure proper storage and to prevent degradation from light.
Discard old solutions: Homemade dilutions have a limited shelf life and should be discarded after approximately 30 days or at the first sign of discoloration.
Never ingest the solution: This guide is for creating a topical antiseptic. Ingestion can be toxic and requires immediate medical attention.

Essential Supplies and Preparation

Before beginning, gather all necessary materials to ensure the process is safe and accurate. This procedure is based on diluting a readily available 10% povidone-iodine (PVP-I) concentrate, a standard stock solution.

Supplies Needed

Source solution: A commercially available 10% povidone-iodine solution.
Diluent: Sterile water or saline is highly recommended to avoid introducing contaminants. Do not use regular tap water for medical applications.
Measuring tools: A graduated cylinder or syringe with clear markings for accurate volume measurement.
Mixing container: A clean, dark-colored glass or plastic bottle for mixing and storage. The dark color protects the solution from light degradation.
Stirring rod: A clean, inert stirring rod or spoon for mixing.
Safety gear: Disposable gloves and protective eyewear are essential to prevent skin and eye irritation.

Step-by-Step Dilution Process

To achieve a 0.5% concentration from a 10% solution, you must dilute the concentrate by a specific ratio. Below is a detailed, step-by-step guide.

Calculation for Dilution

The dilution calculation uses the formula: $(C_1)(V_1) = (C_2)(V_2)$, where:

$C_1$ = initial concentration (10%)
$V_1$ = initial volume (amount of 10% solution)
$C_2$ = final concentration (0.5%)
$V_2$ = final volume (total volume of the diluted solution)

To determine the volumes needed for a specific final volume ($V_2$), you can rearrange the formula to find the volume of the 10% solution ($V_1$): $V_1 = \frac{(C_2)(V_2)}{C_1}$. The volume of the diluent needed is then $V_2 - V_1$. For example, to make a 0.5% solution, the ratio of the 10% solution to the diluent is typically 1 part 10% povidone-iodine to 19 parts diluent.

Instructions for Mixing

Wear your protective gear (gloves and eyewear) before handling the solution.
Measure the diluent: Carefully measure the required volume of sterile water or saline using a graduated cylinder or syringe and pour it into your clean, dark mixing container.
Measure the concentrate: Measure the calculated volume of the 10% povidone-iodine concentrate using a separate, clean measuring tool. Use caution to avoid splashes.
Combine the solutions: Slowly add the 10% povidone-iodine into the sterile water. Do not add the water to the concentrate. Adding the more concentrated solution to the diluent reduces the risk of splashing.
Mix thoroughly: Gently stir the solution with a clean stirring rod until the color is uniform and consistent. Avoid shaking vigorously, which can create foam.
Label and store: Immediately label the container with the new concentration (0.5% povidone-iodine), the date of preparation, and a clear warning for external use only. Store it in a cool, dark place away from excessive heat.

Comparison of Povidone-Iodine Concentrations

Povidone-iodine is available in various strengths, each with distinct uses. The optimal concentration depends on the application, as higher concentrations are not always more effective.


Concentration	Common Use Cases	Efficacy Note	Stability & Shelf Life
10%	Pre-operative skin preparation, topical antiseptic for intact skin.	High initial iodine concentration, but can be irritating and slower drying.	Most stable before dilution, but less active free iodine than more dilute solutions.
7.5%	Surgical scrub, topical use for skin disinfection.	Similar to 10% but often in a lathering formulation for scrubbing.	Relatively stable, but stability can decrease over time.
0.5% (Diluted)	Mucous membrane irrigation (oral/nasal rinses), wound cleansing.	Potentially greater antimicrobial activity against some pathogens due to higher free iodine availability.	Prepared solutions have a shorter shelf life, typically around 30 days.
<0.1%	Very dilute antiseptic irrigation solutions.	Antibacterial efficacy decreases significantly below 0.1%.	Unstable and should be used immediately after preparation.

Safety Precautions and Storage

Homemade solutions of povidone-iodine are not sterile and carry risks. They should only be used for external applications and never for invasive procedures.

Critical Safety Measures

External Use Only: This solution is not for ingestion. If swallowed, seek immediate medical attention.
Avoid certain products: Do not mix povidone-iodine with other antiseptics like hydrogen peroxide, as this can cause harmful reactions.
Allergy awareness: Those with known iodine or shellfish allergies should avoid povidone-iodine products. Discontinue use and consult a doctor if you experience a rash, swelling, or severe irritation.
Keep away from eyes: Avoid contact with eyes. If accidental contact occurs, flush with plenty of cool water for at least 15 minutes and seek medical help if irritation persists.

Storing Your Solution

Label clearly: Mark the container with the contents and creation date to avoid confusion.
Use a dark container: Protect the solution from light exposure, which can degrade its efficacy.
Store in a cool place: Keep it at a controlled room temperature, typically between 15°C and 30°C (59°F and 86°F), away from excessive heat.
Monitor expiration: Due to potential instability, discard homemade diluted solutions after approximately 30 days or if any change in color or smell is noticed.

Conclusion

Making a 0.5% povidone-iodine solution from a standard 10% concentrate is a process that requires precise measurement and careful technique. Following this dilution guide, including the proper safety precautions and storage methods, helps ensure you have a reliable topical antiseptic for appropriate uses. For any medical concerns or to confirm the correct concentration for a specific purpose, always consult a healthcare provider. The safety and efficacy of your solution depend on strict adherence to these guidelines, especially using sterile water and properly labeling and storing the mixture.

For more detailed information on antiseptic solutions and their applications, refer to resources from reputable health organizations.

The Cleveland Clinic provides a comprehensive overview of povidone-iodine uses and side effects.

Frequently Asked Questions

Studies suggest that certain diluted concentrations, like 0.5%, may release more free iodine, which is the active antimicrobial agent, thereby increasing its efficacy against some pathogens in specific applications.

No, it is highly recommended to use sterile water or saline. Tap water contains minerals and contaminants that can reduce the solution's effectiveness and introduce impurities, especially when used for medical purposes.

A freshly prepared diluted solution should ideally be used within 30 days. You should discard it if you notice any changes in color or smell, which can indicate reduced efficacy.

In case of accidental eye contact, immediately flush the eye with a large amount of cool tap water for at least 15 minutes. If irritation or pain persists, seek immediate medical attention.

Homemade diluted solutions may not be sterile. For deep wounds or sensitive medical applications, use commercially prepared, sterile solutions. For minor cuts and scrapes, a freshly prepared solution can be used topically, but always consult a healthcare professional for guidance.

Diluted povidone-iodine is sometimes used as an oral rinse, especially in hospital settings. However, this should only be done under the specific direction of a healthcare provider. Do not swallow the rinse.

Store the original concentrate in its tightly closed, labeled container in a cool, dark place, away from excessive heat and direct sunlight.

The formula used for calculating dilutions is (C1)(V1) = (C2)(V2), where C1 is the initial concentration, V1 is the initial volume, C2 is the final concentration, and V2 is the final volume.