Description

Overview

Hydroquinone is a topical skin-lightening agent used to treat hyperpigmentation, melasma, post-inflammatory hyperpigmentation (PIH), and sunspots. It works by inhibiting melanin production, making it one of the most effective treatments for uneven skin tone and dark spots.

Mechanism of Action

• Inhibits Tyrosinase: Hydroquinone blocks tyrosinase, the enzyme responsible for melanin synthesis, reducing pigmentation formation in the skin.
• Disrupts Melanin Transfer: Prevents melanosomes from transferring pigment to the surrounding skin cells.
• Mild Exfoliation: At higher concentrations, hydroquinone promotes cell turnover, helping to fade dark spots faster.

Benefits and Indications

1. Melasma

• First-line treatment for hormonal pigmentation on the cheeks, forehead, and upper lip.
• Often combined with tretinoin and corticosteroids (Triple Combination Therapy) for enhanced effects.

2. Post-Inflammatory Hyperpigmentation (PIH)

• Lightens acne scars, burns, and dark marks caused by inflammation or injury.
• Effective in treating dark spots from eczema or psoriasis.

3. Sunspots & Age Spots

• Reduces solar lentigines (sunspots) caused by UV exposure.
• Helps fade freckles and uneven skin tone.

4. Off-Label Uses

• Occasionally used for underarm and intimate area brightening (requires medical supervision).

Possible Side Effects

• Common: Mild redness, dryness, peeling, and temporary skin irritation.
• Less Common: Stinging, itching, or sensitivity to sunlight.
• Rare but Serious:
• Ochronosis – A condition where bluish-gray pigmentation develops with prolonged use (>4–6 months).
• Allergic Reactions – Rare, but can cause swelling or severe irritation.

Drug Interactions

• Retinoids (Tretinoin, Adapalene): Often combined for enhanced pigmentation correction but may increase irritation.
• Benzoyl Peroxide: Can oxidize hydroquinone, making it less effective.
• Alpha Hydroxy Acids (AHAs): May enhance penetration but also increase irritation.

Special Considerations

• Pregnancy Category C: Not recommended during pregnancy or breastfeeding.
• Sun Protection is Mandatory: Hydroquinone makes the skin more sensitive to UV rays, so daily broad-spectrum SPF 30+ is required.
• Short-Term Use Recommended: Typically used for 3–4 months, followed by a break to prevent ochronosis.