Yes — and here is the honest list, by active category.
- Topical retinoids (tretinoin, adapalene, tazarotene). Most common: dryness, mild peeling, a temporary worsening of breakouts in the first few weeks (the purge), and increased sun sensitivity. Less common: stinging, redness, or irritation that signals you're moving too fast on the ramp. Daily SPF 30 or higher is part of the protocol.
- Topical antibiotics (clindamycin). Generally well tolerated. Rare: contact dermatitis, very rare gastrointestinal effects with extensive topical absorption.
- Hydroquinone. Mild stinging or redness in the first few weeks; rare cases of contact dermatitis. With prolonged continuous use, rare risk of exogenous ochronosis (a paradoxical bluish discoloration) — a board-certified dermatologist on our medical team will set duration limits to avoid this.
- Eflornithine (in The Hair Reduction Solution). Mild skin irritation, transient stinging, occasional acne-like papules at the application site.
- Azelaic acid. Mild tingling on application that typically eases with continued use.
Across all formulas: stop and message the team if you experience hives, swelling, severe burning, or any sign of allergic reaction. The expected side effects above are different from an allergic reaction in both pattern and severity.