Lac-Hydrin Five 5% (Lactic Acid 5%)
Lac-Hydrin Five 5% is a topical alpha-hydroxy acid moisturizer containing 5% lactic acid, applied twice daily to treat dry, scaly skin conditions such as xerosis and ichthyosis, not actinic keratosis or other dermatologic malignancies.
What It Is
Lac-Hydrin Five 5% contains lactic acid, an alpha-hydroxy acid that acts as a humectant and decreases corneocyte cohesion in the stratum corneum 1. Lactic acid is a normal constituent of blood and tissues. When applied topically, approximately 5.8% is absorbed through the skin after 68 hours 1.
Clinical Application & Dosing
Standard Dosing Protocol
- Apply twice daily to affected areas 1
- For external use only - avoid eyes, lips, and mucous membranes 1
- Can be used safely in infants, children, and adults 1
Application Technique
- Apply thin layer to dry, scaly skin
- Minimize use on sun-exposed areas, particularly the face 1
- If sun exposure unavoidable, protect treated areas with clothing 1
Mechanism & Clinical Effects
At 5% concentration, lactic acid produces:
- Surface and epidermal changes only - does not affect the dermis 2
- Increased epidermal firmness and thickness
- Clinical improvement in skin smoothness 2
- Accelerated epidermal turnover through pH-dependent desquamation 3
Important distinction: The 12% formulation (Lac-Hydrin, not Lac-Hydrin Five) affects both epidermis and dermis, while 5% concentration modulates only surface and epidermal changes 2.
Key Precautions & Adverse Effects
Expected Side Effects
- Transient stinging or burning on abraded skin, fissures, or erosions (e.g., after shaving) 1
- Increased sensitivity on facial application 1
Critical Warnings
- Photosensitivity concern: Long-term photocarcinogenicity studies in hairless mice showed enhanced ultraviolet light-induced skin tumor formation with 12% ammonium lactate formulations 1
- Minimize sun exposure on treated areas
- Potential for post-inflammatory hypo- or hyperpigmentation (not fully studied) 1
When to Discontinue
Stop immediately if skin condition worsens with treatment 1
Special Populations
- Pregnancy: Category B - use only if clearly needed 1
- Nursing mothers: Exercise caution, though lactic acid is a normal constituent of human milk 1
- Pediatric: Safe and effective in infants and children 1
- Geriatric: No dose adjustment needed, but use cautiously 1
Common Pitfalls to Avoid
- Do not confuse with actinic keratosis treatments - The evidence provided discusses 5-FU, imiquimod, and diclofenac for AK 4, but Lac-Hydrin Five 5% is NOT indicated for these conditions
- Do not apply to broken skin immediately after shaving - wait until skin integrity restored to minimize burning 1
- Do not use as monotherapy for photoaging - 5% concentration provides cosmetic benefits but limited dermal remodeling compared to higher concentrations 2