Apple cider vinegar (ACV) is a fermented liquid made from apples. The fermentation process results in acetic acid, which is the primary component that gives ACV its characteristic sour taste and low pH. For centuries, people have used this kitchen staple as a folk remedy, and its application as a popular home treatment for various skin issues, particularly acne, has gained recent attention.
The Proposed Mechanism of Action
The theory behind using ACV for acne centers on maintaining the skin’s protective barrier, known as the acid mantle. Healthy skin is naturally slightly acidic, typically maintaining a pH between 4.5 and 5.5. Acne-prone skin often has a higher, more alkaline pH, which can impair the barrier function. ACV, with a pH of approximately 2 to 3, is thought to help temporarily restore this optimal acidic balance when appropriately diluted.
Acetic acid possesses antimicrobial properties that may help manage acne-causing organisms. The acidic environment can inhibit the growth of bacteria like Cutibacterium acnes (C. acnes), which contributes to inflammatory lesions. ACV also contains alpha hydroxy acids (AHAs), such as malic acid, which function as mild chemical exfoliants. These acids promote the shedding of dead skin cells, helping to prevent the clogged pores that form the basis of acne. However, most evidence supporting ACV’s efficacy is anecdotal, and large-scale clinical trials are lacking.
Safety and Application Methods
Due to its highly acidic nature, proper dilution is mandatory for safe topical application. Applying undiluted ACV (4 to 8 percent acetic acid) can lead to significant skin irritation or chemical burns. A conservative starting point for a facial toner is a ratio of one part ACV to three or four parts water. Individuals with oilier skin may gradually increase the concentration to a maximum of 1 part ACV to 2 parts water, but this must be approached with caution.
Before applying any ACV mixture to the face, a patch test is essential. Apply a small amount of the diluted solution to an inconspicuous area, such as behind the ear or on the inner wrist, and wait 24 hours to check for adverse reactions like redness, burning, or swelling. When used as a toner, ACV can be applied with a cotton pad after cleansing. Initial application frequency should be limited, perhaps once daily or every other day, to assess the skin’s tolerance. The solution can be either rinsed off after a minute or two or left on the skin.
Potential Adverse Effects and Contraindications
ACV is a potent substance, and improper use carries a substantial risk of harm to the skin. The most significant danger is the development of a chemical burn, which can occur from using the vinegar undiluted or leaving a highly concentrated solution on the skin for too long, especially under an occlusive dressing. These burns can result in severe redness, pain, and potentially long-term scarring or hyperpigmentation.
Individuals with existing skin conditions, such as eczema, rosacea, or sensitive or dry skin, should use ACV with caution or avoid it entirely. The innate acidity can exacerbate inflammation and cause flare-ups of these chronic conditions.
ACV should never be applied to broken skin, open wounds, or immediately following aggressive treatments like chemical peels or microdermabrasion. If an individual is already using prescription acne medications, such as topical retinoids or benzoyl peroxide, combining them with ACV can lead to excessive dryness, peeling, and irritation. Consultation with a dermatologist is advised before incorporating ACV into an existing routine.