The Importance of pH In Cosmetics And Skincare


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pH plays a crucial role in the cosmetic and skincare industry as it measures the acidity or alkalinity of a substance. Human skin has a slightly acidic pH level (approximately 5.5) which helps maintain our natural healthy skin barrier known as the acid mantle. Therefore, measuring the pH in cosmetics and selecting pH-balanced cosmetics and skin care products is essential for optimal skin health. 

In the cosmetic world, pH is essential in determining the safety and effectiveness of products. While cosmetic lovers may be aware of pH-balanced products, many do not know the importance of pH in cosmetics.

So, whether you are a cosmetic expert, or are having pH-related issues with your skincare routine, you’ve come to the right place! In this guide, we will discuss the importance of pH in cosmetics, how pH can affect our hair and skin, and how pH influences the overall quality of cosmetic products.

What Is pH?

The pH of a substance is something we learn very early on in chemistry class or when learning about skincare products, but what does it specifically mean?

Well, pH is the measure of how alkaline or acidic a substance is, running on a scale from 0-14 with 7 being neutral, anything below 7 acidic, and anything above 7 being alkaline. 

But for those who skipped chemistry class, or for those who are not cosmetic fanatics, let’s take a close look at some everyday examples that you can find in your supermarket. Let’s start with lemon juice, a well-known, highly acidic fruit with a pH of approximately 2.

On the other end of the scale, we have something like baking soda, with a pH of around 9, this puts baking soda as an alkaline product. Our bodies also have a specific pH which we must balance; the pH of stomach acid is approximately 1.5-3.5, playing a critical role in breaking down the food we eat. 

But, pH is not just important in our stomachs. For example, our skin also has a natural pH level which must be maintained. With a pH of 5.5, human skin protects our bodies from bacteria and harmful substances. Before applying cosmetics and skincare products, checking the pH level is important to prevent disruptions in the skin’s natural balance. It also prevents skin irritation and other issues such as dryness from applying cosmetics with incorrect pH levels. 

What Is Skin pH?

It is estimated that the global cosmetic industry is worth $378 billion (2022), and is set to almost double by 2050. With cosmetics working wonders for people’s skin around the world, there are many people who may not see much of a difference. The secret behind this boils down to the pH of the person’s skin. 

Skin pH differs from person to person, such as the amount of oils and sweat we produce. By understanding the pH of your skin, you can select the best cosmetic products. For those who have acne-prone skin, cosmetics with a low pH can encourage oil production to prevent unwanted breakouts, while for people with sensitive or dry skin, cosmetic products with a high pH level may help soothe irritation or restore moisture in the skin. 

Maintaining a healthy skin pH is not only about selecting the best cosmetic products, but it is also important to practice good skincare routines and habits. For example, avoiding over-exfoliating and using harsh scrubs will help prevent stripping the skin’s natural oils. 

What Is Hair pH?

Before we move onto the importance of pH in manufacturing cosmetic products, it is just as important to discuss hair products, as shampoos, conditioners, and other hair products contribute to the billion-dollar cosmetic industry. 

Apart from the obvious hair appearance, pH plays an important role in hair health. When hair has a healthy pH, the cuticle in the outermost layer of the hair shaft lies flat, like a scale on a fish. This helps control frizz, protects the hair from damage, and keeps it looking smooth and shiny. When the pH of hair rises and becomes alkaline, the hair cuticle lifts and becomes rough, leading to dull-looking hair, dryness, and in some cases, breakage.

On the other hand, if the hair becomes acidic, the cuticles can contract and clamp together, making it challenging for moisture to reach and penetrate the hair shaft. This results in brittle and dry hair. 

The best way to maintain healthy hair is to use pH-balanced cosmetic products that have been specifically formulated to match the pH of hair. Additionally, when using heat styling tools such as hair straighteners or a blowdryer, you should use a pH-balanced heat protector spray and prevent frequent use of these tools which can disrupt the pH balance of your hair and damage your hair’s cuticle structure. 

Factors That Affect Skin & Hair pH

Many factors influence a healthy balance in your skin and hair’s pH. 

Sebum (low pH): In your skin, the sebaceous glands produce an oily substance called sebum which keeps your skin moisturized and protected.

Sweat (slightly acidic pH): Sweating causes a decrease in skin pH.

Harsh Cleansers & Alkaline Soaps: Disrupts the skin’s natural acid mantle, leading to irritation and dryness. Using mild pH-balanced cleansers and soap can prevent this. 

Water Quality: The pH of water used for washing skin and hair typically depends on where your water source comes from. For example, if your water source is soft, it generally will have a near-neutral pH (6-7) because it has a lower level of minerals yet a higher level of sodium. In contrast, hard water is typically alkaline (pH level of 8.5). Water quality can also be influenced by the effects of water pollution, such as contaminated water sources. 

Diet & Hydration: What you eat and drink indirectly affects the pH of your hair and skin. By maintaining a healthy, balanced diet, and staying hydrated, your hair and skin health will improve. 

Environmental: Pollution and other environmental factors such as UV radiation/excessive skin exposure can cause problems with your hair and skin’s natural pH level such as:

  • Hair loss
  • Lackluster locks (loss of pigment – graying hair)
  • Hair aging (thinning of hair follicles)
  • Promoting dandruff
  • Alkaline skin from sun overexposure

Why Is pH Important In Cosmetic Manufacturing?

When selecting cosmetics, we look for the textures, smell, and colors associated with the product, yet the manufacturing of cosmetics goes far beyond that. The pH of cosmetics is often overlooked, and we are here to tell you exactly why it is a crucial factor in the manufacturing of these popular products.

As mentioned, pH tells us a lot about the interaction between cosmetic products with skin or hair. When it comes to manufacturing cosmetic products, the pH plays a pivotal role in ensuring the product’s effectiveness and safety. Therefore, when formulating skincare cosmetics, whether it be in your homemade cosmetic lab, or on an industrial scale, manufacturers must carefully formulate cosmetics with the correct pH level to ensure that they are gentle on the skin. 

The same applies to hair products to maintain both hair health and appearance. 

Cosmetic Ingredients & pH 

A single cosmetic product on average contains 15-50 separate ingredients. With the average woman using 9-15 cosmetic products every day, that is an estimation of 515 individual chemicals used on their hair and skin each day. 

Within this number, some ingredients are sensitive to pH changes. For example, vitamin C is used in numerous cosmetic products because of its antioxidant and brightening properties. But, vitamin C is an ingredient that is extremely sensitive to pH levels and when exposed to the wrong environment, can easily degrade over time, losing effectiveness. This is just one of the many reasons why pH levels must be controlled during the manufacturing process of cosmetics. 

Techniques For Measuring pH In Cosmetics

One way to measure pH in cosmetics is pH strips. pH strips contain chemicals that change color when a reaction takes place from the substance being measured. They are a popular method to measure the pH in cosmetics as it is easy and they provide instant results. 

Measuring Cosmetics With A pH Strip Kit


  • Inexpensive
  • Easy to use
  • Easily accessible
  • Can be used for all cosmetics including emulsions


  • They are not very accurate
  • They are not reliable for people who have color blindness
  • They are single-use – when adjusting cosmetic pH you will need to use a new pH stip, which can result in many being used before the desired pH level is met

Measuring Cosmetics With A pH Meter

Another technique is to use a pH meter. A pH meter is more accurate and advanced than pH strips as it involves a pH probe device that measures the electrical potential difference between a reference electrode and a measuring electrode inside the glass probe.

For accurate results, we recommend our basic Atlas Scientific pH probe kit for cosmetics.


  • Precise measurements
  • The same probe can be reused


  • Expensive
  • They require calibration before use – check out our guide on how to calibrate a pH meter 
  • They need regular cleaning 
  • Proper storage is required
  • An emulsion probe may be required 

Whichever technique you use, it is vital to perform pH testing frequently if manufacturing cosmetics, as the pH level can affect the effectiveness, stability, safety, and interaction the product has with the skin and/or hair. 

How To Measure The pH Of Solid/Non-Aqueous Cosmetics?

Not all cosmetics are in an aqueous form. For example, some shampoos, conditioners, and even toothpaste now come in a solid form. This is because people are starting to be more environmentally conscious, and are opting for products that are plastic-free, or contain more natural ingredients like soy wax. So, how can we determine the pH level of a cosmetic that is solid or non-aqueous?

Typically, pH measurements are taken in aqueous solutions so that electrodes can be inserted directly into the sample. However, solid or non-aqueous products present a unique challenge in measuring pH in cosmetics. This is because these products have a low water content and may not dissolve in water. While it is challenging, it’s not impossible!

To measure the pH of a non-aqueous or solid cosmetic product, you need to use a compatible solvent. This way a solution can be made so that a pH probe (electrode) or pH strip can easily be inserted into the solution. This method allows a measurement to be taken which will reflect the pH measurement of the cosmetic product. 

We must however note… measuring the pH of a non-aqueous or solid cosmetic may not always provide you with accurate results. This is because this ‘alternative’ method involves adding distilled water which has a typical pH value of 7, yet when it comes into contact with air carbonic acid can form, causing the water to become slightly acidic. However, you can still yield valuable information about your cosmetic’s pH level if dilution is the only to measure the pH. 

How To Adjust The pH Of Cosmetics

Once you have measured the pH of the cosmetic, it may need to be adjusted. A simple way to adjust the pH of cosmetics is the use of buffering agents. Buffering agents stabilize the pH level in the cosmetic and prevent it from fluctuating outside the desired range. Buffering agents commonly used in cosmetics include citric acid, sodium hydroxide, and sodium bicarbonate. 

Another way to adjust the pH in cosmetics is by using different acids or bases. Acids like lactic or citric acid can be added to the cosmetic to lower the pH. If you need to raise the pH, bases such as ammonia or sodium hydroxide can be added. When using acids or bases you must take extra caution as they are often potent and may require dilution before use and/or specialized handling – so wear your PPE!

More recently, formulators have become more popular when adjusting the pH in the cosmetic industry. These incorporate ingredients that have inherent pH properties. One example is botanical extracts or oils which have a natural acidity to lower the pH of a cosmetic. Alternatively, to increase the pH natural alternatives such as seaweed/algae or aloe vera can be used. Not only do these natural-based products adjust the pH level, but they also harness beneficial properties for the hair and skin. 

Summing Up, pH Importance In Cosmetics & Skincare

Cosmetics are a billion-dollar industry. Maintaining the correct pH level is vital in cosmetic manufacturing as it ensures that products are effective and safe for our skin and hair.

If you have any questions regarding the pH in cosmetics, which adjusting method we recommend for your cosmetic product, or which pH meter is best for your testing needs, do not hesitate to contact the world-class team at Atlas Scientific.

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