UK researchers from South West Kent Primary Care Trust and the University of Bradford looked at 203 females aged from 13 to 20 who got the medication from family planning clinics and community pharmacies.
They discovered that those who went to a pharmacy to get the morning-after pill obtained it more than twice as quickly as those who went to their local clinic - in 16 hours rather than 41.
Figures from the World Health Organization suggest that taking emergency contraception up to 24 hours after unprotected sex prevents 95 per cent of pregnancies, while taking it between 24 and 48 hours later prevents 85 per cent.
The study also found that:
· Older teenagers tended to seek help quicker, with 14 year-olds taking almost four times as long (37 hours) as 20 year-olds (10 hours).
· The time it took to get the morning-after pill from family planning clinics was much more consistent, with the majority waiting between 38 and 42 hours.
· 72 per cent of those who obtained the morning-after pill from clinics were aged between 15 and 17, while 74 per cent who went to pharmacies were between 16 and 18.
· 25 per cent visited the pharmacy over the weekend and 26 per cent on a Monday.
· Two-thirds of girls under 16 said they needed the morning-after pill because they hadn't used any contraception. The other third blamed split condoms.
· Two-thirds of those in the 16 plus age group sought the morning-after pill because they had had a contraception failure - either the condom had split or they had missed taking the pill.
"The UK currently has the highest rate of teenage pregnancies in Western Europe and the highest rate of live births among teenagers" says Dr Kay Marshall from the School of Pharmacy at the University of Bradford.
"The morning-after pill - often referred to by health professionals as emergency hormonal contraception - has long been recognised as a safe and effective method of preventing unintended pregnancies.
"The name is a bit misleading, because it can actually be taken within 72 hours of unprotected sex, not just the morning after. But as the effectiveness of the morning-after pill declines significantly with time - it works best if taken within 24 hours - it's essential that it can be obtained as soon as possible.
"We believe that the females in our study were able to access the pill much more quickly from local pharmacists as they tend to be open outside normal working hours and at weekends."
The morning-after pill has traditionally been provided free in the UK by family doctors and family planning clinics. It became available over-the-counter at pharmacies in 2001.
Selected community pharmacists can now provide it free of charge to females under 20 as long as they feel that all the appropriate conditions have been satisfied and that she is competent to make the decision to take it.
This is an important development, especially for young girls who can't afford to pay the over-the-counter cost, which recently increased to Ģ25.
Pharmacists providing the item free are required to submit a return to the Primary Care Trust, which includes the age of the client and the number of hours between unprotected sex or contraception failure and dispensing.
The researchers collated data from 116 pharmacy request forms and compared them with 87 requests for emergency contraception from two of the busiest family planning clinics in the Primary Care Trust area.
"Our study suggests that community pharmacists are providing a valuable role in preventing unwanted pregnancies by supplying the morning-after pill and backing this up with advice on contraception and sexual health" says Gaye Lewington from SouthWest Kent Primary Care Trust, which oversees and commissions local health services in the area.
"Recent studies have suggested that allowing pharmacies to supply the morning-after pill does not compromise contraceptive practice or sexual behaviour. This is very important because encouraging females to practice safe sex is just as much a priority as preventing unwanted pregnancies.
"It is essential that the morning-after pill is available promptly if a female feels there is a pregnancy risk, but it is also very important that it continues to be seen as an emergency measure rather than an alternative to using contraception as a matter of routine."