From Wikipedia,
Ammonium lactate
Ammonium lactate Lac-hydrin
Ammonium lactate is a compound with formula NH4(C2H4(OH)COO). It is the ammonium salt of lactic acid. Has mild anti-bacterial properties.
the active ingredient of the skin lotions Amlactin and Lac-Hydrin.[1]
Ammonium lactate is a mix of lactic acid and ammonium hydroxide.
It is used as a skin moisturizer lotion to treat dry, scaly, itchy skin.
Those who are using it should avoid exposure to sunlight or artificial UV rays, such as sunlamps or tanning beds.
Ammonium lactate makes skin more sensitive to sunlight.
Skin is more likely to sunburn. Use sunblock and wear clothes when exposed to sunlight