Hydroquinone
Also known as HQ
The long-standing gold standard for pigmentation. Effective, but designed for defined courses rather than indefinite use.
$15–50 depending on strength and market.
How it works
Inhibits tyrosinase, the rate-limiting enzyme in melanin synthesis, and is cytotoxic to melanocytes at higher concentrations — which is both the mechanism and the source of its risks.
How it's used
2% OTC in some countries, 4% by prescription. Used in defined courses — typically 3–6 months — then cycled off, often alternating with azelaic acid or tranexamic acid. Rigorous sun protection is mandatory or the pigment returns immediately.
Trade-offs
In favour
- Fastest and most reliable topical depigmenting agent
- Decades of clinical use and evidence
- Cheap
Against
- Not intended for continuous long-term use
- Regulatory status varies — restricted or banned in some markets
- Pigment rebounds without sun protection
- Can be irritating
Risks and side effects
- Exogenous ochronosis with prolonged high-concentration use, more common on deeper skin tones
- Irritant contact dermatitis
- Paradoxical hyperpigmentation if misused
- Never combine with unsupervised strong peels
How good is the evidence?
Strong long-standing clinical evidence, tempered by real safety concerns with unsupervised chronic use.
Sources
Sources point to guideline bodies and literature searches rather than single papers, so they stay accurate as the evidence moves.