Two phase 1 patch studies were conducted to evaluate tazarotene foam 0.1% for phototoxic (study A) and photoallergic (study B) potential. In study A, 38 participants were exposed to patches containing tazarotene foam 0.1%, vehicle foam, or no foam (blank patch) over 24 hours. One set each was exposed to UV irradiation, UV and visible (VIS) light, and no irradiation. In study B, 59 participants received patches containing tazarotene foam 0.1% and vehicle foam; sites were exposed to UVB irradiation and VIS light after each application during the induction phase. After 10 to 17 days, participants received both UVA and UVA/UVB irradiation, UVA/UVB plus VIS irradiation, or no irradiation during the challenge phase. Erythema grades and local skin reactions did not differ systematically by study product or across patch sites, and no pattern of increased reactivity at tazarotene foam 0.1% sites was observed. None of the participants demonstrated conclusive photoallergic reactions. Findings suggest that tazarotene foam 0.1% is not a major photoirritant and has a low potential for phototoxic or photoallergic reactions.