Which formulation of tretinoin is considered the most potent and irritating?

The formulation that is considered the most potent and irritating is the 0.1% cream. Tretinoin is a derivative of vitamin A used primarily for the treatment of acne and photoaging, and its potency is closely related to both the concentration of the active ingredient and the formulation type.

While the liquid formulation is often perceived to be more potent due to its vehicle, the cream formulation at 0.1% concentration contains a higher dosage of the active ingredient, which can lead to increased irritation and side effects such as redness, peeling, and dryness. Additionally, the cream vehicle itself can contribute to the potency by enhancing skin penetration, compared to other formulations like gels or foams.

Lower concentrations like 0.05% and 0.02% in various formulations tend to exhibit less irritation. Similarly, the 1% foam may still be effective but does not generally reach the same level of irritation when compared to the more concentrated cream cream formulation. Hence, the cream at 0.1% is recognized for its significant potential for irritation while being effective in treatment.