Intimate Skin Care — pH, Lactic Acid and Safe Ingredients

The unique physiology of the intimate area

The intimate area is one of the most sensitive zones on the body — both in terms of skin structure and its microbial ecosystem. The physiological pH of the vagina in women of reproductive age is 3.5–4.5, which is a distinctly acidic environment. This acidic pH is maintained by bacteria of the genus Lactobacillus, which produce lactic acid and provide natural protection against pathogens.

The skin of the vulva has a slightly higher pH (around 4.5–5.5), but still lower than the rest of the body. Disrupting this delicate environment — through improper hygiene, harsh cosmetics or antibiotics — can lead to fungal infections, bacterial vaginosis and irritation.

pH — the most important parameter of an intimate product

When choosing an intimate wash, the product's pH matters more than a list of trendy ingredients. The rules:

• Women of reproductive age: pH 3.5–4.5 — supports the acidic vaginal environment.
• Pre-pubescent girls and post-menopausal women: pH 5.0–7.0 — adapted to the higher physiological pH during these life stages.
• Men: pH 5.0–5.5 — close to the pH of body skin.

Unfortunately, many popular wash gels, including those marketed as “intimate”, have a pH far from optimal. Always check the pH on the packaging or contact the manufacturer.

Lactic acid — a key ally

Lactic Acid is the number one ingredient in intimate hygiene products. Its role:

• Maintaining acidic pH — it mimics the action of the natural Lactobacillus bacteria.
• Antibacterial properties — it inhibits the growth of pathogens, including Candida and Gardnerella.
• Moisturising — lactic acid is a natural humectant (part of the NMF — Natural Moisturizing Factor).
• Gentle exfoliation — it supports epithelial renewal without causing irritation.

Look for products in which lactic acid (or sodium lactate) appears high on the INCI list — you can check the position of ingredients in our ingredient database.

SLS and SLES — why are they dangerous in this area?

Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES) are harsh anionic surfactants commonly used in shower gels and shampoos. In the intimate area they are particularly harmful because they:

• Damage the lipid barrier of the delicate vulvar skin, increasing TEWL (transepidermal water loss).
• Alter the pH of the intimate environment towards more alkaline values, disrupting the microflora.
• Irritate the mucous membranes — causing burning, itching and dryness.
• Strip away the natural protective layer, leaving the skin prone to infection.

Instead of SLS/SLES, look for mild surfactants: Cocamidopropyl Betaine, Sodium Lauroyl Sarcosinate or Decyl Glucoside. Compare product formulas in our search tool.

Fragrances — the hidden enemy

Intimate hygiene products should be fragrance-free. The term “unscented” does not mean the absence of fragrances — masking fragrances may be added to neutralise odour. The key difference:

• Fragrance-free — no fragrances whatsoever in the formula. This is the safe option.
• Unscented — the product has no noticeable smell, but it may contain fragrances. This does not guarantee safety.

On the INCI list, avoid: Parfum/Fragrance, Linalool, Limonene, Citronellol and other fragrance allergens.

What gynaecologists recommend — and what they don't

The position of gynaecologists on intimate hygiene is clear:

Recommended

• Wash the intimate area externally — the vulva, not inside the vagina.
• Use a dedicated wash with the appropriate pH and lactic acid.
• Wash once or twice a day — no more often.
• Wear cotton underwear and avoid thongs for everyday use.
• Change underwear daily and after exercise.

Not recommended

• Douching (vaginal rinsing) — disrupts the natural bacterial flora.
• Ordinary soap — it has a pH of 9–10, drastically altering the intimate environment.
• Wet wipes containing alcohol — they irritate and dry out the skin.
• Intimate deodorants — fragrances irritate the mucous membranes.
• Washing too frequently — destroys the natural protective barrier.

Probiotics in intimate cosmetics

More and more products contain probiotic strains (e.g. Lactobacillus) or prebiotics that support the natural microflora. Although the concept is promising, the scientific evidence is still limited — topical probiotics may not permanently colonise the intimate area. A more proven approach is to use lactic acid, which supports the existing flora. You can read more about the role of acids and active ingredients in skincare in our guide to active ingredients.

When is a visit to the gynaecologist essential?

Not every intimate discomfort can be solved by switching cosmetics. A visit to the gynaecologist is essential if you notice:

• A change in the colour, smell or consistency of vaginal discharge.
• Persistent itching, burning or pain.
• Recurrent fungal infections (more than 3–4 a year).
• Bleeding after intercourse or between periods.
• Skin changes (lumps, ulcers, discolouration) on the vulva.

Self-diagnosis and self-treatment can delay proper therapy — always consult a specialist about any unusual symptoms.