Since HIV came onto the scene, most of us have been pretty careful about practicing safe sex. However, occasionally things just don’t seem to work out the way that you planned. Things happen in the heat of the moment and caution sometimes goes out the door. Other times, you do all the right things – and then the condom breaks. It’s bad enough when this happens with your regular partner – at least you’re relatively unlikely to pick up an STD – but you could still have an unwanted pregnancy if you weren’t using any other contraception. However, a one-night stand is even worse – you have no idea about the sexual history of the person you had sex with. That’s when the worry really starts.

If you do find yourself sitting on the edge of the bed feeling worried and confused, the first thing to know is that you’re not alone. Three million women in the U.S. have unwanted pregnancies each year, and there are 1.4 million cases of chlamydia and 320,000 case of gonorrhea. There are a lot less HIV infections – about 8000 women each year get HIV from unprotected sex – but given the implications, it’s still something you’ll be pretty worried about.

One of the first things you’ll probably think about is a douche. Don’t bother. Douching is not going to change whether or not you are going to get pregnant – it’s already way too late for that. It also has absolutely no effect on sexually transmitted diseases. On the other hand, it can make it more likely that you will get a pelvic infection – douching messes up the balance of yeast and bacteria in your vagina, making infections more likely. That’s not just after unprotected sex – it may make you feel fresh but it’s not a great idea at any time.

What you can do is to get a morning-after pill. For example, you can buy Plan B over the counter – you don’t need a prescription. It’s pretty expensive – up to $70 – but it’s a lot less costly than the potential consequences of not doing anything. Plan B is effective provided that you take it within three days of having unprotected sex, but don’t hang around – the sooner you take it, the lower the chances you’re going to conceive. There are some minor side effects in some cases – headaches, tender breasts and nausea – but these are mild and go away fairly quickly. Another option is Ella – this is very similar to Plan B and has similar side effects. However, it works for five days rather than three – so if you have been putting off doing anything, this is the one to get.

Another alternative – although it’s much more expensive – is to have a copper UID put in your uterus. This has to be done by a doctor, and you can expect to pay between $500 and $1000 if it isn’t covered on your insurance. This is effective for up to five days after having sex, and will keep on working for at least 10 years – so it may be a good investment, despite the price.

Even if you aren’t pregnant, you need to consider sexually transmitted diseases. If you have any suspicion that your partner might have an STD – or if you don’t know their sexual history – then you need to get yourself tested. STD testing can detect a wide range of infections, including gonorrhea, chlamydia, HIV, hepatitis B and hepatitis C. You will get a report back – here’s an example – which will give you a positive or negative result for each of the diseases. You will then need to get yourself retested for hepatitis and HIV again after six months, just to be sure. It’s okay to wait for a couple of weeks before you get these tests, but, if you suspect that you have been exposed to HIV, don’t wait. Get yourself tested right away and start taking antiretroviral drugs without waiting for the results – doing this can prevent HIV, even if you have been exposed to it.

The other thing you need to do is monitor for any signs that you are pregnant. No contraceptive is completely effective – for example, you have about 2% chance of conceiving if you use a morning-after pill. Keep in mind that a morning-after pill can cause changes to your period, so don’t be alarmed if this happens. However, if your period is more than a week late, it’s time to take a pregnancy test.