Salicylic Acid vs Benzoyl Peroxide for Acne

In the treatment of acne, medications usually try to achieve one or more of the following:

• Reduce sebum production and the rate of keratinization
• Reduce the inflammation associated with acne
• Reduce the number of androgens reaching the follicles and sebaceous glands
• Reduce the population of bacteria, such as Propionibacterium acnes, which colonizes the skin during acne eruption

Acne is most common in adolescents. It often coincides with the onset of puberty when the body changes and the levels of male sex hormones increase. In fact, any physiological change involving hormonal imbalances, especially the increased production of androgens such as testosterone, can trigger the breakout of acne.

The first signs of acne are lesions such as whiteheads and blackheads. These are called comedones and they are formed from the blockage of skin pores by a mixture of dead skin cells, bacteria, and sebum.

Whiteheads are differentiated from blackheads by the color of the specks they leave on the skin. Unlike blackheads, the skin pores are totally blocked in whiteheads. The black specks of blackheads are caused by the oxidation of melanin when exposed to air.

Other lesions present in mild to moderate acne include papules and pustules or pimples. Seborrhea, which is the term for red, scaly skin, is also observed in acne. In severe cases of acne, inflamed lumps called nodules and cysts can be seen. When these are aggravated, they could form acne scars.

Two of the most popular medications for treating acne are salicylic acid and benzoyl peroxide. They are both effective but they do have different mechanisms of action.

What is Salicylic Acid?

Salicylic acid is a phenolic acid that was first derived from the bark of the willow tree. It is a plant hormone and chemically similar to aspirin.

The medicinal value of salicylic acid has been long established. It was mentioned by Hippocrates as a cure for fevers, aches, and pains. Different civilizations from the Assyrians to the Native Americans use the extract of the bark of willow tree for this purpose.

Other plant sources of salicylic acid besides willow tree include tomato, radish, blackberries, blueberries, date, apricot, guava, almond, peanut, olive, and mushroom.

Salicylic acid also has an anti-inflammatory property and a mild antibiotic property. It is included in liniments to treat joint pains and in several topical preparations intended to treat both external skin diseases and internal tissue pain.

Salicylic acid is so useful that some researchers sometimes call it Vitamin S.

This phenolic acid is, however, not without some side effects. When taken orally, salicylic acid can cause gastrointestinal problems such as diarrhea, gastric irritation, and gastric ulcers. It can also cause temporary hearing loss in people with zinc deficiency. It should not be taken by those who show hypersensitivity reactions to the drug.

When used in topical formulations, salicylic acid may cause mild chemical burns, especially in high concentrations. The maximal concentration of salicylic acid permissible in acne products is 3%.

What is Benzoyl Peroxide?

Benzoyl peroxide is one of the most popular organic peroxides. It is included in the WHO list of Essential Medicines because of its usefulness in healthcare.

It is a powerful bleaching agent and is used in teeth whitening and for bleaching hair. Peroxide also has some other industrial uses.

In the treatment of acne, benzoyl peroxide is useful because of its oxidizing and antiseptic properties.

Salicylic Acid and Acne

The properties of salicylic acid that make it useful in the treatment of acne include keratolytic, comedolytic, and bactericidal activities.  It helps break down whiteheads, blackheads, and keratin.

It increases skin turnover by promoting the shedding of the cells of the epidermis; it reduces the sizes of skin pores to prevent them from clogging, and it clears clogged pores to kill the bacteria hiding there.

Other benefits of salicylic acid in acne treatment include its ability to increase blood microcirculation in the skin, and its ability to reduce skin inflammation as well as clear the redness associated with acne. It is especially useful for people with oily skins.

Salicylic acid is available for acne treatment in different forms including as a pad, gel, cream, and lotion. It is found in acne products in strengths varying from 0.5% to 2%. It should be applied on the affected part of the skin and not on individual spots.

Side effects of salicylic acid include skin dryness, flaking, and irritation as well as burning and stinging sensations. These side effects can be worsened in salicylic preparations which also include sulfur, topical retinoids, or benzoyl peroxide.

Benzoyl Peroxide and Acne

Benzoyl peroxide is formulated both as a cream and as a gel for treating acne. It is available in 3 strengths: 2.5%, 5% and 10%.

The 2.5% Benzoyl peroxide is well tolerated and very effective. The higher strengths are not proportionally more effective and they may cause skin irritation.

Topical preparations of benzoyl peroxide may cause skin dryness and irritation at the beginning but such side effects resolve once the skin develops tolerance. These side effects can also be reduced by lubricating the skin with oil-free moisturizers.

However, in a few people, it may worsen the symptoms of acne by causing burning and itching sensations as well as peeling of the skin and swelling. This is why starting with the lowest concentration and then moving on to higher strengths once tolerance has developed is advised.

The peroxide should be applied all over the affected area instead of only on acne spots and lesions. Spot application is not effective.

Benzoyl peroxide is split into benzoic acid and oxygen when it gets in contact with the skin. These two products are non-toxic and this reaction effectively stops the oxidizing action of the peroxide.

Since it is a bleaching agent, benzoyl peroxide can bleach the hair and items of clothing. Therefore, care should be taken when applying the medication.

In acne treatment, benzoyl peroxide works primarily as a peeling agent. It increases the turnover of the skin and removes the mixture of sebum and dead skin cells from the pores.

Furthermore, the peroxide has antibacterial properties and can effectively kill the acne-promoting bacteria colonizing the skin.

Benzoyl peroxide is often combined with other medications known to be effective for treating acne. Common acne remedies that are combined with the peroxide include adapalene, clindamycin, erythromycin, salicylic acid, and sulfur.

Comparing Salicylic acid and Benzoyl Peroxide

Both salicylic acid and benzoyl peroxide are effective anti-acne medications. The choice of which to use largely depends on each user and her skin type. Obviously, those who are sensitive to one of these agents will have to use the one they can tolerate.

Both salicylic acid and benzoyl peroxide work by peeling off the top layer of the skin. By increasing skin turnover, they help the skin heal quicker.

They also both have antibacterial properties which make them useful for treating acne caused by bacteria colonization of the skin.

However, salicylic acid has the added advantage of actively preventing the clogging of skin pores. It does this by constricting these pores so that there is less space for sebum, dead skin cells, and bacteria to occupy.

Therefore, for those with larger-than-normal skin pores, salicylic acid may provide an added benefit. Still, both agents have similar ranges of activity. They are often combined in some acne products to reduce the side effects of each medication.