Girls are being forced to miss school or risk their health as families struggle to afford tampons and pads for them.
The beginning of the year is particularly hard as families juggle other back-to-school costs, Salvation Army spokeswoman Major Pam Waugh said.
"Sanitary products are a basic necessity for women and should not have to be a luxury item, but many of our young Kiwi women are staying home when they have their period, or worse, making makeshift products or recycling old pads so they can still attend school," Waugh said.
"In many cases, this is leading to even more health problems, which means more time off school and additional shame and humiliation for both the girls and the parents."
Labour MP Louisa Wall, The Salvation Army, Countdown and sanitary brand U by Kotex have been working together to highlight the struggle many women face.