Superdrug has become the first high street chain to start selling the morning after pill.
The retailer will sell the emergency hormonal contraceptive (EHC) at £13.49, half the amount women would expect to pay for the branded version in a pharmacy.
The contraceptive is now available at more than 200 Superdrug pharmacies as well as its online doctor service.
Michael Henry, healthcare director at the retailer, said: "We're committed to leading the way in sexual health and offering a generic emergency contraceptive pill at half the price of what's currently available on the high street.
"Its availability will give women more choice and access to this medication at a time when they are most in need."
Until now, women could only get hold of the emergency contraception through an appointment with their GP or by paying around £28 at the pharmacy.
Women buying the pill through pharmacists often need to have a consultation before they are sold the pill, where they are asked questions about the incident - something which has been criticised for making women feel uncomfortable and less likely to seek help when they need it.
The British Pregnancy Advisory Service (BPAS) has campaigned on the issue, calling for a move that would help women get easier access to the medicine.
But critics raised concerns about how many women could use the emergency contraception casually and too often.
Dr Pixie McKenna, Superdrug's health and wellbeing ambassador, and star of Embarrassing Bodies, told Sky News: "The clue is in the terminology - it's for emergencies only and should never be taken more than once in the same cycle.
"If you find yourself taking it on a regular basis it's a sign you need regular contraception, plus you are of course also at risk of STIs, so need a screen."
Dr McKenna says the contraceptive will not be less effective just because it costs less, but can retail at a cheaper price because it does not carry the branding of those available from the chemist.
Ann Furedi, chief executive of the BPAS, said: "We are delighted Superdrug has taken this trailblazing step, and look forward to other major retailers following its lead.
"We know the high cost of emergency contraception can be a major barrier to women accessing it when their regular method fails."
The morning after pill delays the ovaries from releasing an egg and is taken within 72 hours of unprotected sex or if a usual contraceptive has failed.