Consumers no longer have to pay VAT on period pants following a two-year campaign.

The cost of the underwear, seen as a greener alternative to tampons and sanitary towels, will drop by up to £2 on average the Treasury said.

The change came into effect on January 1 and follows the "Say Pants To the Tax" campaign last year.

It was backed by around 80 MPs, charities and retailers including Marks & Spencer and period pants brand Wuka.

Other period products such as tampons and pads have been exempt since 2021 but period pants were classified as garments so were still subject to the tax.

The underwear, which is absorbent, washable and reusable, is seen as more environmentally friendly than single-use products such as menstrual pads. They can also save money in the longer run.

Victoria McKenzie-Gould, corporate affairs director at M&S, said removing VAT would level the playing field in the market for period products.

"Nearly 25% of women cite cost as a barrier to using period pants so we know the new legislation that comes into effect from today will make a big difference to women's budgets across the UK," she said.

Some retailers cut the price of their period pants when they joined the campaign, saying they would absorb the VAT cost themselves. One of those, supermarket chain Tesco, said the price of the underwear would therefore not fall further in its stores as a result of the tax change.

VAT is charged at 20% on most products sold to consumers, but some essential products, including food and children's clothes are exempt.

Nigel Huddleston, financial secretary to the Treasury, said: "It's only right that women and girls can find more affordable options for what has become an essential and environmentally friendly product."

Laura Coryton, founder of social enterprise Sex Ed Matters, said the change could help reduce the stigma around periods which prevents some girls attending school.