With millions of new cases of infections every year in the US, STDs are a danger that everyone needs to be aware of. But while there are thousands of STD testing clinics throughout America offering anonymous STD testing, many people still don't know under what circumstances they should take a test. Here is a list of five occasions when comprehensive STD testing is essential; some of them are common sense (after unprotected sex with a stranger, for example), but some times it isn't so straightforward…

You have a one night stand

Even if you engaged in protected penetrative sex, you may still be at risk of infection – be aware that some STDs, such as herpes, can be transmitted through oral sex. Of course, if you have had unprotected penetrative sex with a stranger, you should strongly consider visiting a local STD testing clinic – if you are concerned about confidentiality, many of them offer anonymous STD testing.

You want to have unprotected sex with a long term partner

Before having unprotected sex with a partner, it is recommended that both you and your partner take some comprehensive STD tests. It is a common misconception that the contraceptive pill protects against sexually transmitted diseases. While the pill does prevent pregnancy, it provides no protection against STDs, and testing is recommended for both you and your partner before you engage in unprotected sex. Many STDs can be completely asymptomatic, so just because you don't have any obvious symptoms does not mean you or your partner haven't been exposed. It may not be very romantic, but STD testing at the beginning of a new relationship is essential for safe health and peace of mind.

You are pregnant

Another strange myth is that pregnancy offers protection against STDs. It does not; more seriously, there are a number of STDs that can cause complications during pregnancy. Some (such as Herpes, HIV and Syphilis) can be passed on to the baby as it is born. Comprehensive STD testing is usually standard procedure in pre-natal medical care at several points during the pregnancy – ask your OBGYN if you need further information.

You have three or more sexual partners in a single year

If you have three or more sexual partners in one year, it is strongly recommended that you undergo comprehensive STD testing, even if you engage in protected sex with all of them. It is also recommended that all sexually active women under the age of 25 should take a Chlamydia test at least once a year, as the disease is extremely common and rarely shows symptoms. If you are worried about your tests appearing in insurance documents, many clinics offer anonymous STD testing.

You have injected drugs or steroids

While some STDs can only be contracted through direct sexual contact, HIV, hepatitis and several other STDs are transmitted through contact with infected blood. The risk is especially high with shared or previously used needles, but if you have ever injected yourself with drugs or steroids you should go to an STD testing clinic to get tested.