Working strengths, vehicles, pH windows and cautions for the actives you will see on a client's compounded prescription. Reference only — estheticians do not prescribe or alter compounded medications.
Tretinoin
Retinoid · Prescription only
0.01% – 0.1%
Compounded strengths let a prescriber titrate between the fixed commercial 0.025 / 0.05 / 0.1 steps, which matters most for sensitive or darker skin where retinoid dermatitis can trigger post-inflammatory hyperpigmentation.
Mechanism
All-trans retinoic acid binds nuclear retinoic acid receptors (RAR-alpha, -beta, -gamma), normalising follicular keratinocyte differentiation, reducing microcomedone formation and upregulating procollagen I and III synthesis.
Evidence
Randomised trials since the late 1980s show measurable improvement in fine wrinkling, roughness and mottled pigmentation over 16 to 48 weeks, and tretinoin remains a first-line comedolytic in acne guidelines.
Vehicle
Anhydrous cream or emollient gel
pH window
5.5 – 6.5
Stability
Photolabile and oxygen sensitive; amber airless packaging, protect from light
Contraindicated in pregnancy. Retinoid dermatitis peaks in weeks two to four. Estheticians do not prescribe or dose it; your role is education, barrier support and pausing exfoliation around treatments.
In the US, OTC sale of hydroquinone products is no longer legal following the 2020 CARES Act reform of the OTC monograph system; the FDA has issued warning letters to companies selling them. Compounded or approved prescription products only.
Mechanism
Competitive inhibition of tyrosinase, plus cytotoxicity to melanocytes at higher strengths, reducing conversion of tyrosine to DOPA and downstream melanin synthesis.
Evidence
Hydroquinone 4% and the triple-combination cream (hydroquinone 4% / tretinoin 0.05% / fluocinolone acetonide 0.01%) remain the most robustly studied topical treatments for melasma, with response typically read at 8 to 12 weeks.
Vehicle
Emollient cream with an antioxidant pair
pH window
6.0 – 7.0
Stability
Oxidises to a brown quinone within weeks; formulations rely on sodium metabisulfite plus ascorbic acid and airless packaging
Cap continuous use at roughly 12 to 16 weeks with rest periods. Prolonged high-strength use risks exogenous ochronosis and confetti-like depigmentation. Strict daily broad-spectrum SPF is non-negotiable.
A rational first choice when rosacea and a pigment component coexist, and one of the few actives generally considered acceptable during pregnancy — that decision belongs to the prescriber, not the treatment room.
Mechanism
A saturated dicarboxylic acid with antibacterial activity against Cutibacterium acnes, comedolytic keratinocyte effects, competitive tyrosinase inhibition and scavenging of neutrophil-derived reactive oxygen species.
Evidence
Approved for acne (20% cream) and papulopustular rosacea (15% gel/foam); trials support comparable acne efficacy to benzoyl peroxide 5% and tretinoin 0.05% with a milder pigment risk profile.
Vehicle
Cream or gel; requires high-shear mixing or a milled dispersion
pH window
4.5 – 5.5
Stability
Chemically very stable; gritty and poorly tolerated if particle size is not reduced
Transient stinging and warmth in the first one to two weeks is expected; tell the client in advance or adherence collapses.
The most useful tolerance-builder in a compounded regimen — it softens the irritation profile of retinoids and acids without competing for the same receptor.
Mechanism
Precursor to NAD+ and NADPH; increases ceramide and free fatty acid synthesis to improve barrier function, and reduces melanosome transfer from melanocytes to keratinocytes.
Evidence
Controlled studies show reduced transepidermal water loss, improved barrier recovery, and modest hyperpigmentation improvement at 4% to 5% over 8 to 12 weeks; it also reduces sebum output in some cohorts.
Vehicle
Aqueous gel, serum or lotion
pH window
5.0 – 6.5
Stability
Hydrolyses to nicotinic acid at low pH or under heat, which is what produces flushing — avoid formulating below pH 4
Benefit plateaus around 5% while flushing and irritation reports rise; higher is not better.
Usually prescribed alongside a nightly retinoid, with a benzoyl peroxide wash in the morning.
Mechanism
Binds the 50S bacterial ribosomal subunit to inhibit protein synthesis, suppressing Cutibacterium acnes and reducing follicular inflammatory mediators.
Evidence
Guidelines are unambiguous that topical antibiotics should be combined with benzoyl peroxide or a retinoid; fixed-dose clindamycin/BPO combinations outperform either agent alone and blunt resistance.
Vehicle
Hydroalcoholic solution, gel or foam
pH window
4.0 – 6.0
Stability
The phosphate ester hydrolyses at pH extremes; beyond-use dating for compounded aqueous preparations is short and often refrigerated
Never used as monotherapy — antimicrobial resistance develops quickly. Courses are time-limited, typically reassessed at 12 weeks.
Targets the inflammatory and vascular drivers of melasma that tyrosinase inhibitors alone miss, which makes it a useful partner during hydroquinone rest periods.
Mechanism
A lysine analogue that blocks plasminogen binding to keratinocytes, reducing plasmin-driven release of arachidonic acid and prostaglandins that stimulate melanogenesis; it also dampens the vascular component of melasma.
Evidence
Meta-analyses of oral, topical and intradermal tranexamic acid in melasma report significant MASI reductions versus baseline, with oral routes generally strongest and topical use well tolerated.
Vehicle
Aqueous serum or light emulsion
pH window
5.0 – 6.0
Stability
Chemically stable; preservation is the critical control because the base is water-rich
Topical use has a low systemic burden, but any oral adjunct requires a prescriber to screen thrombotic and hormonal risk factors. That conversation is outside esthetic scope.
The main non-prescription option when hydroquinone is unsuitable or during mandated rest periods. Applied for 15 minutes and rinsed, rather than left on overnight.
Mechanism
An aminothiol metabolite of cysteine that inhibits tyrosinase and peroxidase, chelates copper and iron, and raises intracellular glutathione, shifting melanogenesis away from eumelanin.
Evidence
Randomised double-blind work shows cysteamine 5% significantly reduces melasma pigment versus placebo, and a head-to-head trial reported efficacy comparable to a modified Kligman formula with fewer irritation withdrawals.
Vehicle
Cream applied as a short-contact mask, then rinsed
pH window
4.5 – 6.0
Stability
Readily oxidised and strongly malodorous; commercial products use stabilised, sealed packaging and short application windows
Odour is the leading reason clients quit — set expectations at the consultation. Expect transient erythema and stinging.
Pairing 15% ascorbic acid with 1% alpha-tocopherol and 0.5% ferulic acid both stabilises the system and increases photoprotection versus vitamin C alone.
Mechanism
Donates electrons to neutralise reactive oxygen species, regenerates oxidised vitamin E, and acts as a cofactor for prolyl and lysyl hydroxylase in collagen synthesis while inhibiting tyrosinase.
Evidence
Percutaneous absorption work established that the free acid must be formulated below pH 3.5 to remain uncharged and penetrate, with skin levels saturating around 20%; clinical studies support photoprotective and pigment benefits alongside sunscreen.
Vehicle
Anhydrous or low-water serum, often with tocopherol and ferulic acid
pH window
Below 3.5 for the free acid
Stability
Oxidises to dehydroascorbic acid on exposure to oxygen, light, heat and trace metals; yellowing signals loss of activity
The low pH stings compromised barriers and stacks badly with same-session acids or a fresh retinoid start. Discard once it turns amber.
Short-contact washes deliver most of the antibacterial benefit with far better tolerance than leave-on high strengths.
Mechanism
Decomposes on skin to release free oxygen radicals that non-specifically kill Cutibacterium acnes, with mild keratolytic and comedolytic action and no documented bacterial resistance.
Evidence
Trials show 2.5% is as effective as 10% with markedly less irritation, and adding benzoyl peroxide to a topical antibiotic both improves clearance and suppresses resistance.
Vehicle
Wash, gel or cream; aqueous suspension
pH window
3.0 – 6.0
Stability
Thermolabile oxidiser that degrades with heat; store below room temperature and away from light
Bleaches fabric and hair. Do not layer in the same application as tretinoin, which it oxidises; morning wash, retinoid at night.
Self-neutralising: the visible white pseudofrost is precipitated acid, not frosting from protein denaturation. Rinse rather than neutralise chemically.
Mechanism
A lipophilic beta-hydroxy acid (pKa around 2.97) that partitions into sebaceous follicles, dissolving desmosomal attachments between corneocytes and reducing follicular plugging; it is also anti-inflammatory.
Evidence
Serial 20% to 30% salicylic acid peels show comparable acne clearance to glycolic acid peels with a lower post-inflammatory hyperpigmentation rate in Fitzpatrick IV to VI skin.
Vehicle
Hydroalcoholic or glycolic-free ethanolic solution
pH window
3.0 – 4.0 leave-on
Stability
Stable; crystallises out of solution if the solvent system is thinned or chilled
Avoid large-surface high-strength application in pregnancy and in salicylate sensitivity. Keep total treated area conservative to limit systemic absorption.
Most valuable as a rotation agent that keeps pigment suppressed during hydroquinone rest periods.
Mechanism
A fungal metabolite that chelates the copper at the active site of tyrosinase, blocking the rate-limiting step of melanin synthesis.
Evidence
Comparative studies place kojic acid 2% behind hydroquinone 4% as monotherapy, but show useful additive effect when combined with glycolic acid or hydroquinone.
Vehicle
Cream or gel with a chelating agent
pH window
4.0 – 5.5
Stability
Discolours in the presence of metal ions and light; disodium EDTA is standard
A recognised contact sensitiser. Patch test, and avoid stacking with high-strength acids on the same night.
0.5% – 1% (compounded pigment creams use 0.01% fluocinolone instead)
Present in a compounded formula to buy tolerability, not as a treatment in its own right.
Mechanism
A low-potency corticosteroid that binds cytoplasmic glucocorticoid receptors, suppressing inflammatory cytokine transcription and, incidentally, melanocyte activity.
Evidence
The steroid component of triple-combination melasma creams both blunts retinoid and hydroquinone irritation and independently contributes to depigmentation in comparative trials.
Vehicle
Cream or emollient ointment
pH window
4.5 – 6.5
Stability
Stable across normal storage conditions
Short, supervised courses only. Prolonged facial use causes atrophy, telangiectasia, steroid rosacea and perioral dermatitis, plus rebound on withdrawal.
