Vitamin A comes in several forms. The strongest is called retinoic acid which, because of its strength, may cause adverse reactions. Therefore, this active form of retinol is not suited to all skin types. Retinoic acid creams are only available with prescription from a doctor or dermatologist. Because of its potency it’s classed as a pharmaceutical and not a beauty product.
Retinoic acid is not a new product. It has been clinically tested and is used in skin care for almost three decades. Some of these studies, instigated by the observation that oral vitamin A improved the appearance of keloid scars, have examined the effects of the topical use of this potent vitamin A on scars.
Conclusion of examining these reports is that the use of topical retinoic acid on scars, although seemingly effective, is not recommended. This because of potential side effects.
One study report is titled: Reduction of Keloids and Hypertrophic Scars Following Systemic Administration of Vitamin A:
[..] examined the effect of a topically applied 0.05% solution of retinoic acid on keloids and hypertrophic scars. [..] Slight to marked reduction of the size of these scars and a decrease of complaints such as itching were noted in the majority of the cases.
In addition, Hansen reported a 75% subjective and objective improvement in scars as old as three years old treated with a 0.05% topical retinoic acid. This improvement meant softening and flattening of hypertrophy and fading of the scar’s color once the effects of the acid had worn off.
In his series, vertical scars on the abdomen and those across the lines of minimum tension elsewhere on the body showed the most dramatic improvement. Areas that did not seem to respond well were the breast, chin, and jawline.
Another report by Daly et al.  presented the results of a randomized, double-blind, prospective study on the effects of topically applied vitamin A:
A statistically significant difference (20% reduction in scar size) was noted between the group treated with 0.05% retinoic acid and the control group treated with the base cream.
In the retinoid-treated group, lesion size was reduced by approximately 20%. Daly and coworkers concluded that the clinical effects of retinoids had been demonstrated to be consistent with the in vitro data.
In some case scarring actually was the result of inappropriate use of 0.05% retinoid gel. Gels seem to provoke skin irritation more often than retinoin creams .
Topical retinoids may be absorbed in the body. Therefore it may cause side effects due to excessive vitamin A (specifically retinoid) intake (hypervitaminosis). Especially for those who take vitamin supplements.
Another possible side effect is damage to unborn children (teratogenicity). So pregnant women should steer clear of retinoic acid.
Because of these possible complications and the absence of sufficient research data some experts do not recommend the use of topical retinoic acid on scars.
I would personally opt for silicones because these have no side effects. In case silicone sheeting doesn’t catch on I would possibly consult my doctor about retinoic acid treatment for scars. Although I think steroid injections would be a more appropriate next step.
Maybe prolonged use of an retinyl palmitate or retinol cream could help fade scars. Since these creams are rather safe to use and easy to obtain (I would advice to always start moderately with new skin care products to monitor the results) such creams may offer a valuable addition in case other treatments don’t work.
Read more about the topical use of retinol creams on scars.
 Janssen de Limpens AMP: The local treatment of hypertrophic scars and keloids with topical retinoic acid. Br J Dermatol 103:319, 1980
 Daly T, et al. A double-blind placebo-controlled efficacy study of tretinoin cream 0.05% in the treatment of keloids and hypertrophic scars. J Invest Dermatol 1986;86:470.
 Hogan DJ: Scarring following inappropriate use of 0.05% tretoin gel. J Am Acad Dermatol 17:1056, 1987