In healthy women, vaginal discharge is made up of fluids released by glands in the uterus, cervix, and vagina. It carries dead cells and bacteria out of the body, and helps keep the vagina clean. However, not all types of vaginal discharge are normal. Some of them are a sign of diseases, especially gynecological infections.

In this text, we will address the causes of vaginal discharge, detailing the signs that may indicate vaginitis or cervicitis (inflammation of the vagina or cervix).

Physiological vaginal discharge

Before we start talking about physiological vaginal discharge, that is, the normal vaginal discharge that is not related to diseases, we have to remember a few details about the anatomy of the female reproductive system.

The confusion between vagina and vulva is very common. When we look at the female external genitalia, what we see is the vulva. Without the aid of special devices, we can only see the external orifice of the vagina, because the vagina itself is an elastic and muscular canal located inside the body, connecting the uterus to the outside world, as can be seen in the illustration below.

female reproductive system


The vaginal discharge usually originates in the vagina or in the cervix and only becomes noticeable when it leaks through the external orifice of the vagina.

All women at reproductive age may have a “normal” vaginal discharge, called physiological discharge. This type of discharge has a daily volume of 1 to 4 ml, and is formed by the combination of dead cells, natural bacteria of the vaginal flora mucus. Its function is to moisten, lubricate and keep the vagina clean, healthy and free of infections.

Physiological vaginal discharge is stimulated by estrogen and, therefore, may increase in periods in which there is increased hormonal stimulation, such as during pregnancy, use of estrogen-based contraceptives, in the middle of the menstrual cycle, near the time of ovulation or days before menstruation.

Normal vaginal discharge usually has the following characteristics: it can be thick, watery or stretchy; its color is white, milky or transparent; and it has very mild odor or no odor at all.

One of the most important tips for identifying a physiological discharge is the absence of signs and symptoms of irritation, such as pain, burning, redness or itching of the vagina. However, it is important to note that a mild vulvar irritation may occur in some women with physiological discharge.


A pathological vaginal discharge, also called leukorrhea, occurs when the woman has a gynecological disease. This type of discharge can have several causes, the most common is vaginitis, which is a infection of the vagina, usually caused by bacteria or fungi. The pathological discharge can also occur due to atrophy of the vaginal mucosa after menopause, an allergy to some substances – like spermicides -, or the presence of a foreign body inside the vagina.

In the following lines we will briefly discuss the main causes of vaginitis and vaginal discharge.


Candida is a fungus that lives on our skin and gut and does not usually cause symptoms. However, whenever there is some derangement in the immunological balance of our body, as in cases of trauma, excessive use of antibiotics, stress, diabetes, immunosuppression, etc., Candida can start to multiply excessively, become invasive and cause symptomatic vulvovaginal disease

Vaginal candidiasis frequently manifests as itching and/or burning on the vulva, painful urination and pain during sexual intercourse. The vaginal discharge is usually odorless, thick and whitish, often compared to cottage cheese.

Gonorrhea and Chlamydia

Gonorrhea and Chlamydia are two sexually transmitted diseases (STDs) caused, respectively, by the bacteria Neisseria gonorrhoeae and Chlamydia trachomatis. Both infections cause cervicitis (infection of the cervix) with vaginal discharge, usually mucopurulent (cloudy yellow). Other symptoms include pain to urinate and pain during sexual intercourse, usually with postcoital bleeding and irritation of the vulva.

If you want to read more about chlamydia, click on the following link: CHLAMYDIA – Symptoms, Transmission and Treatment.


Trichomoniasis is a sexually transmitted disease caused by a protozoan called Trichomonas vaginalis. Vaginitis caused by trichomoniasis usually presents with a thin yellow-green discharge with an unpleasant odor, associated with other classic signs of vulvovaginitis, such as pain when urinating, vulvar irritation and bleeding/pain during intercourse.

Trichomonas vaginalis can remain asymptomatic for a long time, making it difficult to know exactly when the contamination occurred.

For more information about trichomoniasis, see: TRICHOMONIASIS – Symptoms, Transmission And Treatment.

Bacterial vaginosis

Bacterial vaginosis is the main cause of abnormal vaginal discharge. It is an infection caused by changes in the natural flora of the vagina, which results in a reduction of the number of lactobacillus (the “good” bacteria) and an excessive growth of aerobic bacteria (the “bad” bacteria), like Gardnerella vaginalis, Mycoplasma hominis, Prevotella, Porphyromonas, Bacteroides, Peptostreptococcus, Fusobacterium and Atopobium vaginae.

It is very common to associate bacterial vaginosis with the bacterium Gardnerella vaginalis, however, this disease is caused by the growth of multiple bacteria, not just Gardnerella. The term vaginosis is used instead of vaginitis in this case because there is little or no inflammation of the vagina, just bacterial proliferation.

The typical symptom of vaginosis is a thin, grayish vaginal discharge with an unpleasant “fishy smell”. Other symptoms of vulvovaginal inflammation, such as painful urination, itching of the vulva and pain with intercourse are absent in most cases.

The proliferation of bacteria and the decrease in the number of lactobacilli causes a significant increase of the pH of the vagina, which is one of the clues for the diagnosis.

Vaginal atrophy

Vaginal atrophy, also referred to as vulvovaginal atrophy or postmenopausal atrophic vaginitis, is characterized by dryness, inflammation, and thinning of the epithelial lining of the vagina due to decreased estrogen levels.

Estrogen keeps the vagina healthy and moist. When it is lacking, it causes vaginal atrophy that leads to pain when urinating, more frequent urinary tract infections, discomfort during sexual intercourse and vaginal discharge, that can be yellow and malodorous.


Allergies to condom lubricants, spermicides, perfumes, soaps, fabric softeners, douches or intimate toiletries can cause an allergic reaction in the vagina/vulva, leading to the onset of discharge, that us usually clear and itchy.


  • HPV infection.
  • Genital herpes.
  • Cervical cancer.
  • Semen allergy (rare cause).
  • Vulvovaginitis caused by Streptococcus bacteria.
  • Foreign body retained inside the vagina (internal absorbent or “lost” condom, for example).
  • Pinworm infection.


Clear discharge

Clear discharge is usually normal, especially if there are no other symptoms associated. It may have an egg-white like consistency. Ovulation, pregnancy and sexual arousal can also produce a clear discharge.

Brown discharge

A brown discharge usually contains coagulated blood. It can be caused by remnants of menstruation, traumas, infections, foreign bodies, gynecological cancer, implantation of the embryo in the uterus in the first days of pregnancy, vaginal atrophy or ectopic pregnancy.

Yellowish discharge

Yellowish vaginal discharge is usually a sign of gynecological infection, especially if it is accompanied by a bad smell, burning or vaginal itching. Trichomoniasis is perhaps the main cause of this type of discharge, but other infections can also cause it, such as gonorrhea and chlamydia.

White discharge

White discharge can be normal, especially if it is thin and in small quantities. Thicker, greyish discharge, usually associated with irritating symptoms, such as itching and vaginal pain, may be candidiasis. If there is an unpleasant fishy smell, vaginosis is a possibility.

Discharge with odor

Vaginosis and trichomoniasis are the main causes of strong-smelling discharge.


In order to properly distinguish all types of vaginal discharge, it is necessary to consult with a gynecologist. Through gynecological examination, it is possible to discover if there is vaginitis, cervicitis, signs of vaginal atrophy or if it is just a physiological discharge without signs of inflammation. It is also possible to sample the discharge for evaluation of vaginal pH, microscopic investigation, and culture.


There is no single treatment that works for all types of vaginal discharge. The treatment depends on the cause. For example, yeast infections are usually treated with antifungal medication, bacterial vaginosis and trichomoniasis  are treated with antibiotics, and atrophic vaginitis with vaginal moisturizing agents and hormonal therapy.

If you have vaginal discharge, make an appointment to see your gynecologist, so the cause can be clarified and proper treatment can be instituted.

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