It makes sense that most of us dive into a new relationship armed with little shiny packets. After all, if you're having sex early on in a relationship, it's likely that you won't know much about your partner's sexual history yet. But how much more do you know a few months later when you've run out of condoms and the temptation to rely on the fact that you're in a 'long-term relationship' creeps in?

According to a survey by Playing Safely, only one in five couples get tested for STIs before ditching the condoms and a whopping 73% of people questioned (aged 16-30) didn't think to discuss their sexual history with a new partner. What's more, 63% of people who have had unprotected sex have never had an STI check-up.

I'm protected against pregnancy

"I have a contraceptive implant, so I knew there was little risk of pregnancy," says Sarah. As with most couples, preventing an unplanned pregnancy was her biggest concern. But the Health Protection Agency reports that nearly 400,000 STI diagnoses were made in 2008 alone. With such dramatic figures, making sure you're sexually healthy should be up there competing for your attention, as Sarah soon found out.

"Me and my bloke abandoned condoms about a week after first sleeping together. Neither of us worried about it too much as we didn't have any symptoms of STIs," she says. "Then recently I started having irregular bleeding and abdominal pain. The symptoms turned out to be side-effects from the implant, but I still had to have tests just in case. Waiting for the test results was horrible. I knew that if they were positive we would both have to contact exes, and that one of us could have infected the other. It's definitely taught me to get tested first."

Remember, it's not just penetrative sex that transfers STIs. You can catch chlamydia, herpes, syphilis, LGV and gonorrhoea from having unprotected oral sex. The HPV virus, which can cause warts and (though rarely) cancer, can also be caught from having oral sex. Make sure you're protected and practice safe oral sex by using a condom or dental dam.

I don't have any symptoms

According to genitourinary medicine (GUM) consultant Dr Patrick French, ruling yourself out of the STI game due to a lack of symptoms doesn't guarantee you're both in the clear.

"However well you know your partner, some STIs have no symptoms. So even though you or your partner may not look or feel like you have an infection, it doesn't necessarily mean that you are free of STIs and should stop using condoms," he says. "In fact, over two thirds of women with chlamydia - the UK's most common STI - have no symptoms, and without being tested will not know that they have it."

But my partner's 'clean'

It's a pretty grim picture that makes you want to dive into the nearest GUM clinic before you can say 'sexually transmitted infection', but before you start panicking, see how your loved one fares in an open, honest conversation. Consider the following:

How much do you know about your partner's sexual history?

How much is your partner willing to reveal about their sexual history?

Are you both willing to be tested before ditching the condoms?

How much do you trust your partner: are they being sexually monogamous - and are you?

Now I'm not so sure

If you're even slightly unsure about any of these points, it's best to either get tested or keep the condoms close by - or even consider ditching your partner if they're not prepared to be adult about it. As Nicola puts it: "Me and my boyfriend were both virgins before we met, and neither of us had even had any other sexual activities with other people either, so I felt confident about not using condoms. I'd definitely get tested if we broke up now and I entered a new relationship. I'd make the lad get tested as well or he's getting nowhere!"

Updated: 15/08/2011

Written by Hannah Jolliffe