The NHS in the UK should provide a wider range of condoms to people requiring contraception, family planning campaigners have said.
People need condoms of different sizes and shapes, campaigners say
The Family Planning Association (FPA) warns different sizes and shapes should be available to help people avoid unwanted pregnancy and infections.
An FPA survey of 500 people found a third had experienced a condom splitting or coming off during sex.
The Department of Health said local clinics controlled provision.
The FPA issued its warning at the beginning of sexual health awareness week.
Two thirds of those in its survey who had experienced problems with a condom did not know why.
And a quarter of respondents did not know condoms came in different lengths and widths.
Just under half said talking about condom size was embarrassing.
The FPA says one of the main factors which affects whether a condom is going to split or slip is its fit.
People who have had problems can also lose confidence in using condoms as a contraceptive, it warned, potentially increasing their risk of unwanted pregnancy or a sexually transmitted infection.
Toni Belfield of the FPA said: "Men come in different shapes and sizes and so do condoms.
"Poor use of condoms can have devastating consequences on people's sexual health.
"Recent new figures showed the UK has the highest ever number of new cases of chlamydia and continued high rates of unwanted pregnancies."
She added: "The NHS is the largest distributor of free condoms in the UK.
"We would like to see a much wider variety of condoms made available so that people can chose a fit that is right for them from a good selection.
"We would also like to see health professionals talk to clients about condoms during consultations and tackle some of the embarrassment that exists around condom use."
A spokeswoman for the Department of Health said: "Used correctly, condoms provide the best protection against sexually transmitted infections.
"Primary care trusts are responsible for meeting the sexual health needs of their local populations.
"It is for local sexual health clinics to decide on the range of condoms they make available and distribute free of charge."
She said sexually transmitted infections had increased over the years but nationally the rate of increase was now slowing down.
"Gonorrhoea cases fell by 13% between 2004 and 2005. Already 54% of patients are seen within 48 hours reflecting a 9% increase since May 2005," she said.