Women can now buy a morning-after pill that works up to five days after sex, without having to see a doctor.
But there are concerns that the pill will encourage promiscuity and it can act as an early form of abortion.
The Co-operative Pharmacy is selling the pill in 40 branches for £30 to women over 18.
EllaOne can be taken longer after sex than the conventional morning-after pill, which works up to three days after sex and could also cause an early stage abortion.
Norman Wells, director of the charity Family Education Trust, said: “When the morning-after pill was first licensed for use, the government gave assurances that it would be kept under the control of doctors and only supplied on prescription in exceptional circumstances.
“But since it has been made available over the counter in pharmacies, and in some parts of the country is being provided free of charge to girls and young women, its use has multiplied.”
He said, “young people in particular have been lulled into a false sense of security, taken a more casual attitude to sex, and become exposed to an increased risk of sexually transmitted infections”.
Maria Macgregor, of the charity Life, said: “Ethical concerns around these kind of pills are often overlooked. One of the ways in which they can work, as the manufacturers themselves say, is by preventing the implantation of an already fertilised embryo.
“There is even some evidence that provision of these pills can actually worsen rates of unplanned pregnancies and sexually transmitted infections.
“This may be due to risk-compensation, when the existence of a perceived safety net encourages less cautious behaviour.”
A spokesman for The Co-operative Pharmacy said the pill would be made available in 40 branches in “areas of high demand” including Essex, London and Bristol. If it was proved successful it would be rolled out throughout its 760-strong network.