So, in the last week I’ve been sent some patch test information that has been shared by a large brand to their followers.  Around 200 of you sent this to me, as the information doesn’t seem accurate 

So, as you know Brow Geek NEVER brand bashes, but let me explain what we should do if patch testing is required in your country or state.


Patch testing as a method for assessing allergic reactions was first introduced in the early 20th century. The concept of patch testing to identify contact allergies was pioneered by Josef Jadassohn, an Austrian dermatologist, and further developed by Josef Holubar, a Czechoslovak dermatologist, in the early 1900s.

Patch testing involves applying small amounts of allergens or irritants to the skin, typically the back, under an occlusive patch for a specific period to observe for any skin reactions or sensitivities. This method allows dermatologists and healthcare professionals to identify substances that may trigger allergic contact dermatitis or other skin reactions in individuals.

Since its inception, patch testing has become a widely used technique in dermatology and allergology to diagnose and manage contact allergies, irritant reactions, and other skin disorders caused by exposure to various substances. The technique has evolved over the years with the development of standardized allergen series and improvements in patch test methodology for better accuracy and reliability in diagnosing allergic contact dermatitis.

WHY 24-48 HOURS 

The 48-hour duration for patch testing on the skin when assessing for contact dermatitis or eczema is based on the delayed nature of allergic contact reactions. Allergic contact dermatitis is a type of skin reaction that occurs when the skin comes into contact with an allergen to which the individual is sensitized, leading to an immune response.

Here's why a 48-hour patch testing period is typically recommended:

1. **Delayed Reactions**: Allergic contact reactions can be delayed, meaning that a reaction may not occur immediately after exposure to an allergen. The 48-hour timeframe allows for observation of both immediate and delayed reactions that may develop over time.

2. **Sensitization**: It takes time for the immune system to recognize and react to an allergen. For individuals who are sensitized to a particular substance but have not previously shown symptoms, the 48-hour duration is necessary to allow the immune response to develop.

3. **Accurate Diagnosis**: Longer periods of exposure provide a more comprehensive assessment of the skin's reaction to potential allergens, increasing the likelihood of identifying the specific substances that may be causing the allergic contact dermatitis or eczema.

4. **Standard Practice**: The 48-hour patch testing period has become a standard practice in dermatology and allergology for evaluating contact allergies and assessing skin sensitivities. It allows for a thorough evaluation of the skin's response to potential allergens.

By maintaining the patch test on the skin for 48 hours, healthcare professionals can gather more information about a person's skin sensitivity or allergic reactions to specific substances. This information is crucial for developing an effective treatment plan and avoiding future exposure that could trigger dermatitis or eczema flare-ups. 


Patch testing for beauty treatments, such as hair dyes, eyelash extensions, brows and so on, has become more common in recent years as awareness of skin sensitivities and allergic reactions has increased. While the exact date of when patch testing for beauty treatments specifically began is not widely documented, it has likely evolved alongside advancements in dermatology, cosmetic science, and consumer awareness.

With the rise of social media, online forums, and consumer advocacy, there has been a growing emphasis on safety, product transparency, and skin health in the beauty industry. As a result, beauty professionals and individuals have recognized the importance of patch testing to assess potential allergic reactions and skin sensitivities before using certain products or treatments.

Patch testing for beauty treatments is now considered a best practice in salons, spas, and skincare clinics to ensure client safety and minimize the risk of adverse skin reactions. Many cosmetic manufacturers and beauty professionals recommend patch testing as a standard procedure before applying certain products, particularly those that are more likely to cause skin irritation or allergic responses, and in some countries, it’s a legal requirement as part of your insurance coverage.


When conducting a patch test for a brow tint or lamination product, it is important to follow the specific instructions provided by the manufacturer. However, as a general guideline for brow product patch tests:

1. **Recommended Time**: Brow product patch tests are applied to the skin for between 15 and 30 minutes, typically. Then assess the skin for the next 48 hours to assess for any skin reactions or sensitivities.

2. **Patch Test Area**: Apply a small amount of the brow tint product on the inner forearm. These areas are commonly used for patch testing due to their sensitive skin and lower visibility,  always use strongest colour/shade as ths contains the highest % of chemicals. 

3. **Apply and Wait**: Follow the instructions provided with the brow tint product to apply a small amount of the tint to the test area. Allow the product to develop on the skin for the recommended time, this is between 15-30 minutes, 

4. **Observation**: Over the 48-hour period, check the patch test area for any signs of redness, itching, swelling, or other skin reactions. If no reaction occurs, it is generally safe to proceed with using the product for brow tinting, remember skin can change and as humans we can have a reaction at anytime, even to chemicals that have never caused a problem before

Few things to note, some of these chemicals are strong and there is a misconception between beauty standards and testing for irritants/eczema and so on. We are not checking the skin for these types of reactions, we are checking for allergic reactions and irritation. 

We DO NOT leave on the skin for longer than is required for the treatment, if this is a 15 minute skin stain, or a 30 minute lamination, then this is what we follow 

We DO NOT cover with tape or other adhesives etc. 

It's important not to cover a beauty treatment patch test with tape because it can interfere with the test results. The purpose of a patch test is to determine if a product causes any adverse reactions when applied to a small area of skin. If the patch test area is covered with tape, it can prevent air from circulating and may lead to inaccurate results.

As we discuss above, leaving under an occlusive patch or for 48 hours is the general dermatology testing, and this is not what we are doing, understanding the difference is important when working with chemicals that can break down the disulphide bonds of hair, or known allergens such as PPD, as this can cause extreme irritation, and contact dermatitis. 

So be safe, be sensible, and educate for the health of your client at all times. 

Debs xoxo


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