A group of researchers tested 32 commercial sunscreens for their ability to stain white and black 100% cotton.

Of the tested sunscreens; Alba Botanica Hawaiian SPF 50 Spray, L’Oreal Invisible Protect SPF 50, Solbar Thirty, and Aveeno Protect and Hydrate SPF 50 were among the most staining sunscreens.

The least staining sunscreens were; Cerave Baby, Solbar Zinc 38, Cerave Face SPF50, and Babyganics Mineral Based SPF 50

Using statistical analysis to group the sunscreens by sunscreen ingredients they created four distinct groups. Based on these groupings they tested 8 sunscreen ingredients; Avobenzone, Homosalate, Octinoxate, Octisalate, Octocrylene, Oxybenzone, Titanium Dioxide, and Zinc Oxide.

For white fabric; Avobenzone was a strong yellow stainer and so was Oxybenzone to a lesser extent. Titanium Dioxide and Zinc Oxide both left faint white stains.

For dark blue fabric; Avobenzone and Oxybenzone both left faint white staining, but Titanium Dioxide and Zinc Oxide left strong white stains.

The sunscreen ingredients were applied directly to the fabric, whereas in real-life it’s likely transferred to skin by friction and smearing throughout the day

A sunscreen that stains is by no means a reflection of its ability to protect your skin from UV. If reducing extrinsic photoaging is a goal, it’s important to use a sunscreen frequently. Often people are discouraged from using sunscreens because of the texture, scent, and in some cases staining of their clothes.

If staining is an issue I’ve had good luck with soaking it with 99% isopropyl alcohol and then a soak in sodium percarbonate (Oxiclean) or hydrogen peroxide.

Cornell also has a great stain guide for a myriad of stains.

Ginnetti M, Buhnerkempe M, Wilson M, The staining of clothing by
sunscreens: a pilot study, Journal of the American Academy of Dermatology (2018), doi: 10.1016/j.jaad.2018.02.022

"What’s causing sunscreen to stain clothing?" on KindofStephen.