This effect was even stronger than that
of 1% hydrocortisone in placebo gel, but weaker compared
to that of the commercially available corticosteroids.
It is striking that the hydrophilic placebo gel used
as negative control also showed a significant anti-inflammatory
effect comparable to the effect of A. vera gel
(97.5%) 48 h after administration. However, the effect of
the A. vera gel can hardly be attributed to placebo effects
because additional constituents make up only 2.5% in the
A. vera gel. The success of the gel base might be explained
by a refrigerant effect or specific effects of the gel compounds,
such as glycerol or phenoxyethanol. Interestingly,
1% hydrocortisone in placebo gel was less effective after
48 h than the placebo gel or A. vera gel (97.5%) whereas
1% hydrocortisone in the base of a cream efficiently
reduced erythema after 48 h. Presumably, the gel base
may inhibit the effects of hydrocortisone.