Wrinkles

Photoageing and loss of elasticity.

Sunscreen

An ingredient class — not a single line on an ingredient list

An Australian trial randomised 1,621 people and followed them 4.5 years. Squamous cell tumour incidence was 39% lower (1,115 vs 1,832 per 100,000); basal cell carcinoma showed no difference. This is one of the few entries on this site carrying strong evidence.

Moderate evidenceRetinoid⚠ In pregnancy Do not use

Retinol

In a vehicle-controlled trial, 0.4% retinol applied for 24 weeks moved the fine-wrinkle score by −1.64 against −0.08 for vehicle. Thirty-six people, and it was forearms, not faces. In pregnancy, guidance says do not use it.

Moderate evidenceAntioxidant

Niacinamide

In a 12-week split-face study of 50 people, 5% niacinamide reduced fine lines, yellowing, red blotchiness and pigmented spots. The control was not nothing but the same moisturiser, and the manufacturer paid for the trial.

Moderate evidenceAntioxidant

Vitamin C (ascorbic acid)

Ascorbic Acid

In pig skin, L-ascorbic acid entered only when formulated below pH 3.5, and 20% was the concentration for optimal absorption. Pure ascorbic acid is not among Korea's listed whitening actives; four of its derivatives are.

Moderate evidenceAntioxidant

Bakuchiol

In a 12-week double-blind trial of 44 people, bakuchiol 0.5% and retinol 0.5% reduced wrinkle area and hyperpigmentation to a similar degree, with more irritation on the retinol side. With no vehicle arm, the trial cannot say what the improvement on either side was due to.

Ingredient dataOther

Adenosine

At 0.04% a product can be filed as a wrinkle-improvement functional cosmetic without submitting data. But the only human trial we found in the published literature had 22 participants, and its comparator was not vehicle but another adenosine formulation.

Not establishedHumectant

Collagen

The rule of thumb in the skin-penetration literature is 500 daltons. Collagen is hundreds of times larger. That applying it increases collagen in the dermis has not been established in people.

Medicines used for this concern

Medicines are not listed alongside cosmetic ingredients. Dosage and whether a prescription is needed are settled in consultation.

Tretinoin Prescription only

Clinical procedures related to this concern

Procedures are not listed alongside topical ingredients. They are not something you use at home.

Botulinum toxin Injection
PDRN Injection
Polynucleotides (Rejuran) Injection