Soaps or Cleansers: Which Is Better for Acne-prone Skin?

Washing the skin is important because it removes dirt, sweat, and excess skin oil and allows acne medications to penetrate into the skin.

However, some soaps and cleansers can irritate your skin, and when it comes to caring for acne-prone skin, reducing irritation is crucial. 

All soaps are irritating, so it is best to completely avoid using soap on any area of acne-prone skin.

When it comes to cleansers, the ideal cleanser for acne-prone skin needs to be gentle, meaning that it needs to be:

• Non-irritating: It should not over-dry the skin or be harsh to it.
• Non-comedogenic: It should not clog skin pores.
• Non-allergenic: It should not trigger an allergic reaction, such as redness, swelling, itching, or a rash.¹

To understand why all soaps and some cleansers irritate the skin more than others, we need to take a quick look at how soaps and cleansers work.

Caution - Deep Science Ahead: We are about to take a deep dive and understand all there is to know about soaps vs. cleansers, how they work and affect the skin, the various types of each, and how to choose the right one.

If you're simply interested in what to use when washing your acne-prone skin, it is fairly simple: Never use soap. Instead, use an ultra-gentle liquid cleanser that is specifically made for the face.

How Soaps and Cleansers Work

If you have ever tried to make your own salad dressing, you probably know that oil and water do not mix. When you wash your skin with just warm water, without using a soap or cleanser, the water does not sufficiently mix with any grease or oil that may be on your skin. As a result, too much oil or grease may still remain on the skin surface.

This is why you need the help of a cleanser to remove oil or grease from the skin. Soaps and cleansers contain ingredients called surfactants, which is short for "surface active substances." Surfactants act as go-betweens, allowing for oil and water to mix, and facilitating the removal of oil and dirt from the skin during washing.

What's the Difference Between Soaps and Cleansers?

Now that we know how soaps and cleansers work, let's examine the differences between them in order to understand why cleansers are better for acne-prone skin.

1. Soap -- the oldest known type of surfactant: The word "soap" refers to a specific class of substances made by a process called saponification, which involves cooking a fat or oil together with a chemical like sodium hydroxide.
2. Cleanser -- technically known as syndet -- a newer type of surfactant: The word "syndet" is short for "synthetic detergent." There are many different types of syndets, and therefore many different methods of making them.

Both soaps and syndets can come in either bar or liquid form.

The Ingredients in Soaps and Cleansers

Ingredients in soaps

People have been producing soap for thousands of years, and it remains popular today. However, not everything that we call "soap" in everyday language is actually soap in the chemical sense. True soap is made by a process, called saponification, involving two components.

1. A fat or oil
2. A base (a type of chemical that is not acidic, such as sodium hydroxide)²

You can usually tell which fat or oil and which base were used in making a particular soap by looking at the names of the ingredients. The second part of the chemical name usually comes from the fat or oil, and the first part, from the base.

The table below shows common soap ingredients. The component in red comes from the fat or oil, and the component in blue comes from the base.

If you are not sure whether a product is an actual soap, check the list of ingredients on the back of the product. If any of the ingredients appear in the table above, avoid using the product, and opt for a cleanser instead.

Ingredients in cleansers

What we call "cleansers" in daily life are technically known as syndets (synthetic detergents). Manufacturers have been making syndets since the late 1940s, and there is no single method of producing them.

Similar to soaps, syndets contain surfactants as the main ingredients, but syndet surfactants are different from soap surfactants. There are four types of surfactants found in syndets.

1. Anionic (negatively charged)
2. Cationic (positively charged)
3. Amphoteric (containing both positive and negative charges)
4. Nonionic (not charged)²

A cleanser can contain several different types of surfactants together. The types of surfactants in a cleanser determine how harsh that cleanser will be on the skin. In general, we can rank surfactants in cleansers as follows, from the harshest to the mildest:

1. Anionic
2. Amphoteric
3. Nonionic

Cationic surfactants are rarely incorporated into cleansers, so we do not have enough data on how irritating they may be to the skin.

How Soaps and Cleansers Affect Acne-prone Skin

People with acne typically produce too much skin oil, some of which ends up on the skin surface and gives the skin a greasy appearance. To effectively wash off this excess oil and to prepare the skin for acne treatments, either soap or cleanser is required.¹

On the other hand, soaps and cleansers can interfere with the skin barrier--in other words, they can damage the skin. This means that while we cannot do away with using a soap or cleanser, we need to select the gentlest one possible to avoid damaging the skin. Since research shows that cleansers tend to be less harsh to the skin than soaps, it is better to use a cleanser, and to choose the mildest one.^3-11

Potential side effects of soaps and cleansers

Both soaps and syndets can cause side effects. These can include:

• A feeling of skin dryness
• Scaly, rough skin
• Skin redness, irritation, and itching

Soaps are more likely than syndets to cause side effects. In addition, if you have "hard water" in your home, which would mean it contains many minerals, washing your skin with soap may react with the minerals to create residues that can clog skin pores. As a rule of thumb, acne-prone people should avoid using soap.

The surfactants in modern facial cleansers are usually relatively mild and rarely produce major side effects. Still, people with acne-prone skin should choose the gentlest cleanser possible, and be careful to choose one specifically made for the face. It can also be helpful to look for terms like "mild," "for sensitive skin," and "hypoallergenic" on the label.

Choosing the Right Cleanser

The table below lists some common cleanser ingredients, which we have ranked from harsh to mild. When you buy a cleanser, check the ingredients on the back and do your best to avoid any products that contain ingredients that are labeled as "harsh" in the table. If any of the "medium" surfactants are included in the first seven ingredients in the cleanser, it may also be best to keep shopping for a milder cleanser.

Another approach to testing the harshness of your cleanser

Besides viewing the list of ingredients, there is another way to test the harshness of your cleanser--if you're feeling extremely motivated. For example, if none of the ingredients listed on the back of your cleanser are in this table, you can still gauge how harsh the cleanser will be by buying something called a pH tester at your drugstore. A pH tester is usually a paper strip that you can dip into the cleanser.

When you dip the paper strip into your cleanser, the strip will change color. Each color corresponds to a particular pH (acidity/basicity level), which you can look up on the color chart that comes with the pH tester. In general, you should use cleansers that possess a pH between 4 and 6, as these match the natural pH of human skin and are thus less likely to cause problems.^5-7

Based on the evidence, we recommend the following guidelines for choosing a soap or cleanser.

1. Avoid soap. If you are not sure whether a product is soap, check the list of ingredients on the back. If any of the ingredients are found in the table of soap ingredients in this article, do not use the product.
2. When choosing a cleanser, select the mildest one possible. You can check the list of ingredients on the back of the cleanser and consult the table of cleanser ingredients in this article. Avoid any ingredients that are labeled as "harsh" in the table and "medium" if they are within the first seven ingredients listed.
3. Choose cleansers made specifically for the face.
4. If possible, choose cleansers with a pH (acidity level) between 4 and 6. Unfortunately, the pH value usually is not provided on product labels, but pH testers are available at any drugstore and are easy to use. But don't worry, most liquid facial cleansers that specifically state that they are "ultra-gentle" should be within this pH range. 
5. Select liquid cleansers rather than bars. This is important for 2 reasons. First, because the closed container helps prevent contamination by microbes (bacteria or mold). This is especially important if you are sharing the cleanser with other people. And second, research also suggests that the pH of liquid cleansers is closer to the pH of the skin compared to cleansing bars.⁵
6. Look for terms like "mild," "for sensitive skin," and "hypoallergenic" on the label. While these terms are unregulated, they at least indicate the manufacturer is considering these things.
7. Choose a fragrance-free cleanser whenever possible. Research shows that fragrances are a common cause of skin irritation, and it is important to avoid skin irritation if you are acne-prone.⁴ Look for a cleanser labeled "scent-free" or "fragrance-free."

And remember, do not wash your skin more than two times a day. More than that can be irritating, and to get acne-prone skin clear, it is vital to keep it non-irritated.