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Retinoids

Retinal (retinaldehyde)

Also listed as retinaldehyde

One conversion step from retinoic acid, so more potent than retinol. In a trial it reduced wrinkles alongside tretinoin, with less irritation.

Limited evidenceTypical strength: 0.05-0.1%

What it is

Retinaldehyde sits between retinol and retinoic acid in the skin's vitamin A pathway, so it needs only one step to become active. In a randomized trial, 0.05% retinaldehyde and 0.05% prescription retinoic acid both reduced wrinkles over 18 weeks compared with vehicle, and retinaldehyde caused less irritation.

It is less common than retinol because it is harder to stabilize, and product strengths (usually 0.05-0.1%) are often not shown.

How strong is the evidence?

Limited evidence

A randomized trial of 125 people with sun-damaged skin found 0.05% retinaldehyde and 0.05% retinoic acid both reduced wrinkles and roughness at 18 weeks versus vehicle, with retinaldehyde better tolerated. Earlier work showed dose-dependent retinoid activity in human skin at 0.05-0.5%. The evidence base is small.

What it's used for, checked

Wrinkles and sun damage

Holds up

Reduced wrinkle and roughness measures versus vehicle at 18 weeks.

Gentler than prescription tretinoin

Holds up

Caused less irritation than retinoic acid in the head-to-head trial, though it can still irritate.

Acne

Unproven

Has retinoid and antibacterial activity, but few acne trials.

Don't combine with

  • Strong exfoliating acids or benzoyl peroxide on the same night
  • Other retinoids

Who should be careful

  • Avoid during pregnancy and while trying to conceive. Oral retinoids cause birth defects; a 2015 meta-analysis of about 650 exposed pregnancies found no clear rise in birth defects from topical retinoids, but it was too small to call them safe, so the standard advice is to stop.
  • Start a few nights a week; dryness and peeling are possible.
  • Use sunscreen by day.

The studies

Every citation is checked against its PubMed record.

  1. Profilometric evaluation of photodamage after topical retinaldehyde and retinoic acid treatment.
    Creidi P, Vienne MP, Ochonisky S, Lauze C, Turlier V, Lagarde JM, et al. · Journal of the American Academy of Dermatology · 1998 · RCT

    125 people with photodamaged faces used 0.05% retinaldehyde, 0.05% retinoic acid or vehicle; both actives reduced wrinkle and roughness measures at 18 weeks, and retinaldehyde was better tolerated.

  2. Topical retinaldehyde on human skin: biologic effects and tolerance.
    Saurat JH, Didierjean L, Masgrau E, Piletta PA, Jaconi S, Chatellard-Gruaz D, et al. · Journal of Investigative Dermatology · 1994 · Human biological + tolerance study

    Retinaldehyde at 0.05-0.5% produced dose-dependent retinoid effects in human skin, such as a thicker epidermis and more cell turnover; in 229 patients, 0.05% and 0.1% preparations were well tolerated on the face for up to 3 years.

  3. Pregnancy outcomes following first-trimester exposure to topical retinoids: a systematic review and meta-analysis.
    Kaplan YC, Ozsarfati J, Etwel F, Nickel C, Nulman I, Koren G · British Journal of Dermatology · 2015 · Meta-analysis

    Across 654 pregnancies exposed to topical retinoids in the first trimester and 1,375 unexposed, there was no significant rise in major birth defects, miscarriage, low birthweight or prematurity; the authors call this reassuring after accidental exposure but too limited to justify using retinoids in pregnancy.