After puberty, having vaginal discharge is normal. The exact amount varies by person, but normal vaginal discharge is clear to white in color, has minimal or no odor, and can be thick, thin, or sticky depending on how much of the hormone estrogen you have in your body. Estrogen levels can be affected by certain types of birth control, where you are in your menstrual cycle, or if you are pregnant. Normal vaginal discharge can also vary due to changes in diet, fluctuating stress levels, and having sex.

However, if you notice a change in the amount of discharge, color, or odor it may be time to see your health care provider. If you have vaginal discharge that has a color (meaning that it’s not clear or white) or a bad odor, or if the discharge comes with irritation, itching, pain, or discomfort while having sex, you might have an infection. Some infections that can cause abnormal vaginal discharge are sexually transmitted, but others are just a result the normal vaginal bacteria being out of balance. Regardless, if you ever have a concern about your vaginal discharge, make an appointment with your medical provider and have it checked out.

The most common causes of abnormal vaginal discharge caused by an infection are:

Bacterial Vaginosis (BV)

BV is a very common infection caused by an imbalance in the natural vaginal flora, the good bacteria that are part of a normal, healthy vagina. Most people with BV notice a thin, grey or off-white discharge with a fishy odor. BV can be caused by sex with a new partner (although it’s not a sexually transmitted infection) or use of a product, like a douche, that upset the balance of normal bacteria in the vagina. BV can also be caused by irritants, like soaps with fragrance, or objects that stay in the vagina too long, like tampons or dislodged condoms.

Most people notice the odor caused by BV after they have sex or at the end of their period. While BV can sometimes resolve on its own, waiting it out with an odor and discharge can be irritating and may increase your chances of getting a STI, so antibiotic pills or creams from a health care provider are the treatment of choice.

Vaginal Candidiasis (Yeast Infection)

Candidiasis is a fungus that thrives in dark, wet places and usually causes a thick white discharge sometimes described as being similar to cottage cheese or tofu. People with yeast infections may also notice severe itching and irritation. They may have swelling, soreness, or even small tears in the vagina or vulva.

Yeast infections can be caused by wearing tight, non-breathable clothing or underwear, wearing wet clothing for too long (like bathing suits), having high blood sugars, taking antibiotics (since they kill off both good and bad bacteria, upsetting the balance in the vagina), and using birth control with high levels of estrogen. If you do get a yeast infection, treatment options are either an antifungal cream or pills.

Sexually Transmitted Infections (STIs)

STIs are passed between partners during sex. While there are many STIs, trichomoniasis, gonorrhea, and chlamydia are the ones that are the most likely to change your vaginal discharge. With a trichomoniasis infection, you may notice a green, yellow, or frothy discharge, itching, and/or a bad odor. Gonorrhea and chlamydia usually cause no symptoms at all but can cause a greenish or white discharge, irritation, or itching. All three of these infections have to be diagnosed by a health care provider and treated with antibiotics, and all three can be prevented by using condoms, internal condoms, and/or dental dams when you have sex.

Since people who have an STI sometimes don’t have any symptoms, talking to your health care provider and getting checked (even if your discharge is normal) are the only ways to know for sure if you have an STI. You should get checked every time you have a new partner. Otherwise, talk to your provider about your individual level of risk and how often you should be screened. For most people, that’s at least once a year.

The bottom line is that most vaginal discharge is expected and natural. However, if you’re having vaginal discharge that has a bad smell or is uncomfortable or you’re not sure if it’s normal, make an appointment with your health care provider to have it checked out and to discuss possible causes and treatment options.