The government has lowered to 15 the age at which girls can buy the morning-after pill without a prescription.
And the Food and Drug Administration also says the emergency contraception no longer has to be kept behind pharmacy counters.
Those seeking Plan B One-Step previously had to be 17 or older to buy it. But a federal judge in New York told the government to lift all age restrictions on the drug.
Judge Edward Korman blasted the Obama administration for imposing the age-17 limit, saying it had let election-year politics trump science and was making it hard for women of any age to obtain the emergency contraception in time. He ordered an end to all age restrictions by Monday, for Plan B and its generic versions.
Tuesday's decision will allow the pill to sit on drugstore shelves next to condoms, spermicides and other health products. But customers must prove their age at the cash register.