Mucus Plug vs. Vaginal Discharge: What’s the Difference?

Key takeaways:

• There are different types of glands in the vagina, including secretory and mucous glands.
• The uterus is in the pelvis, but a portion of it protrudes through the back of the vagina, ending as an opening called the cervix, which has mucus glands.
• Cervical mucus, sometimes accumulating and organizing as a plug, can become dislodged from your cervix and be seen exiting the vagina intact or in pieces.
• It can be difficult to differentiate between normal vaginal discharge and a mucus plug, but understanding what separates them can help you decide how to proceed with treatment.

Vaginal discharge is a natural feature of a healthy reproductive system. While discharge may change in thickness, color, and consistency, it is usually a normal occurrence and not cause for concern.

The presence of a mucus plug is sometimes confused with normal vaginal discharge, but they are two separate conditions. Vaginal secretions making up a vaginal discharge are much different from mucus in consistency, appearance, and function. A mucus plug occurs during pregnancy and is characterized by a collection of mucus in the cervix.

Overview: differences between mucus plug and vaginal discharge

Mucus and vaginal discharge originate from different types of glands and different parts of your vagina. Vaginal glands make watery secretions, while the mucus glands of your cervix in the rear of your vagina make a thicker, gel-like secretion that can organize into what is often called a mucus plug. Whether you’re pregnant or not makes a huge difference in how you experience both mucus and vaginal secretions.

Definition of mucus plug

The mucus plug is mucus that sticks together in a single semi-liquid lump. The mucus made by your cervical glands is much thicker than the watery secretions made by vaginal glands. It has a structure that allows it to sit in place at the closed opening of your cervix (known as the os), where it is altered in different ways by your hormones.

For example, its architecture can become streamlined to allow easy passage of sperm through the os on a journey to fertilize an ovulated egg. It can also, however, change its consistency to become a barrier to infectious organisms to protect your baby when you’re pregnant or prevent infection of your pelvis when you’re not pregnant.

Mucus is made by the mucus glands of the cervix. These are made up of cells that are different from vaginal cells; their cells are also different from those of the rest of your uterus. Even though the cervix is that part of your uterus that protrudes through the back of your vagina, the differences in cell types allow it to act as if it were a different type of organ altogether.

Definition of vaginal discharge

The vaginal discharge you see is merely a secretion of the vaginal glands. These can include:

• Skene’s glands. These are a pair of glands that sit on either side of where your urine exits (urethra).
• Bartholin glands. These are a pair of glands that sit on either side of the lowermost part of your vaginal opening.
• Transudate. A transudate is something that passively filters, like water does, through the layers of cells of your vaginal walls from deeper layers.

While cervical mucus also contributes to your vaginal discharge, they are best described separately.

Key differences between mucus plugs and vaginal discharge

The watery secretions of your vagina are not organized structurally like cervical mucus is. While mucus has a complicated infrastructure of organized molecules, a vaginal discharge is made up of much simpler substances that function to hydrate your vaginal tissue, provide lubrication during intercourse, and even provide antibiotic properties to keep infections from rising into your bladder or your uterus and pelvis.

Appearance

The increased density of mucus makes it less transparent. This gives it a slightly grayish appearance. However, the slimy nature of the mucus itself can make it glisten a bit, causing it to appear lighter in color.

Whether mucus sticks together in one plug or is discarded naturally with movement or intercourse allows it to vary in appearance from a single glob to stringy strands of mucus. They can become stretchy around the time of ovulation and hold together tightly at other times.

Vaginal secretions are naturally released during sexual arousal, but that is something you notice physically rather than see. Because all vaginal secretions are diluted to begin with, they may be difficult to notice unless they have a color.

A clear to grayish color is common for vaginal secretions; a pinkish tint may signal you’re ready to start a period. However, dark, yellow, green, or red colors signify trouble, such as from a hormone imbalance or an infection.

Timing

Vaginal secretions are continuously secreting moisture, and they can increase with sexual arousal. However, mucus experiences something akin to a turnover, a loss of mucus or an organized mucus plug, followed by the generation of more mucus or a new plug. This can happen after the mechanical action of intercourse or tampon removal, or even with exercise that causes it to detach from the cervix. It can also occur due to hormonal changes during the menstrual cycle.

Pregnancy is a different subject altogether:

• Vaginal secretions become thicker during pregnancy due to the action of hormones.
• Mucus becomes thicker to seal the cervix away from threats such as viruses, bacteria, and fungus.

Purpose

Vaginal secretions keep the vaginal walls’ cells moist, which is important for their cellular health. They also provide lubrication for the mechanical actions of intercourse to protect delicate vaginal cells from abrasions and injury due to friction.

Mucus, typically clumping into a plug in the cervix, functions to protect your inner uterus from infection, which can threaten pregnancy loss or even be life-threatening. When not pregnant, it is also protective. The cervix, although described as closed, is really just a reapproximation of its circular fibrous and muscular fibers. Therefore, it’s not bacteria-proof unless there’s also a mechanical obstruction; the mucus plug is that obstruction.

Normal vs. abnormal

Both mucus and vaginal secretions change over the course of your menstrual cycle, although both become thicker as you approach midcycle’s ovulation time, mainly due to the change in cervical mucus. Thickness is not a concern, as this normally changes over the month.

What is not normal, however, is a foul or unpleasant odor or symptoms such as pain, itching, or burning. Although a pink tinge is normal before your period, bleeding or blood is never normal except during your expected period. Colored mucus or secretions can be associated with infections and need to be evaluated by a doctor.

When to see a doctor about a mucus plug or vaginal discharge

Whether you notice mucus or an actual plug depends on whether you lose mucus all at once or as fragments over time. A vaginal discharge, like mucus, is normal, but there are exceptions for both that warrant seeking professional medical care.

You should see a doctor about a mucus plug if:

• You’re pregnant.
• Your cycles are irregular.
• It is accompanied by blood, whether you are pregnant or not.
• It is accompanied by an unpleasant odor, whether you are pregnant or not.
• It is associated with symptoms such as pain, itching, or burning, whether you are pregnant or not.
• If it is discolored dark (brown, black), green, red, or yellow, no matter if you are pregnant or not.

You should go to the emergency room for a mucus plug if:

You are not pregnant and

• You also have a fever.
• You have pelvic pain.
• There is a foul odor.
• It is an unexpected color.
• You have pain with urination or bowel movements.
• You have bladder or back pain.
• You have rectal pain.
• You have painful intercourse.
• There is bleeding, or there are clots present.

When you are or might be pregnant, go to the emergency room if you experience any of the above symptoms and

• There is bleeding, or there are clots.
• You are having contractions.
• Your cycles are irregular.

You should see a doctor about vaginal discharge if:

• It is continuous. This is especially true if you’re pregnant, and if your provider is not immediately available, you should go to the emergency room.

You should go to the emergency room for vaginal discharge if:

• It is sudden or continuous if you’re pregnant.
• It is accompanied by blood, pregnant or not.
• You have a fever.
• It is accompanied by an unpleasant odor, pregnant or not.
• It is associated with symptoms such as pain, itching, or burning, pregnant or not.
• If it is discolored dark (brown, black), green, or yellow, whether you are pregnant or not.
• You are pregnant and have contractions.

Questions to ask your doctor about mucus plugs or vaginal discharge

Whether you’re pregnant or not, a sudden appearance of a mucus plug or a change in vaginal discharge should raise the following questions.

Questions to ask about your mucus plug:

• Can this be normal?
• How will you make the diagnosis?
• What if I’m pregnant or might be?
• Could this be an infection, and if so, should we involve my partner in evaluation and/or treatment?

Questions to ask about vaginal discharge:

• If this isn’t my normal discharge, can it still be normal?
• How will you make the diagnosis?
• Could this be an infection, and if so, should we involve my partner in evaluation and/or treatment?
• What if I’m pregnant, might be, or want to be?

Mucus plugs and vaginal secretions: apples and oranges

Mucus plugs and vaginal secretions are different substances, come from different glands, and have different functions. Whether they’re normal or not depends on the accompanying symptoms, but when pregnant, it’s best not to take any chances and see your provider right away.

General Medicine follows a strict editorial process, including using real experts to write our articles, vetted primary sources, fact-checking, a secondary medical review, and updates as necessary. This article was medically reviewed and fact checked by Dr. Lane Thaut, DO.

Sources

Lacroix, Guillaume, et al. "The cervicovaginal mucus barrier." International Journal of Molecular Sciences, 2020, https://www.mdpi.com/1422-0067/21/21/8266.

Adnane, Mounir, Meade, Kieran, O'Farrelly, C. “Cervico-vaginal mucus (CVM) - an accessible source of immunologically informative biomolecules.” Vet Res Commun, December. 2018, doi: 10.1007/s11259-018-9734-0, PMID: 30117040, PMCID: PMC6244541, https://pmc.ncbi.nlm.nih.gov/articles/PMC6244541/.

Tung, Chih-Kuan, Tung, Suarez, Susan. "Co-adaptation of physical attributes of the mammalian female reproductive tract and sperm to facilitate fertilization." Cells, 2021, https://www.mdpi.com/2073-4409/10/6/1297.

Prendiville, W, Sankaranarayanan, R. "Anatomy of the uterine cervix and the transformation zone - Colposcopy and Treatment of Cervical Precancer.” IARC Technical Report, No. 45, 2017, https://www.ncbi.nlm.nih.gov/books/NBK568392/.

Vagios, Stylianos, Mitchell, Caroline M. "Mutual preservation: a review of interactions between cervicovaginal mucus and microbiota." Frontiers in Cellular and Infection Microbiology, 2021, https://www.frontiersin.org/articles/10.3389/fcimb.2021.676114/full.

Dong, Mengting, et al. "Interactions between microbiota and cervical epithelial, immune, and mucus barrier." Frontiers in Cellular and Infection Microbiology, 2023, https://www.frontiersin.org/articles/10.3389/fcimb.2023.1124591/full.

Dwyer, Peter L. "Skene’s gland revisited: function, dysfunction and the G spot." International Urogynecology Journa, 2012, https://link.springer.com/article/10.1007/s00192-011-1558-1.

Thiyagarajan, Dhanalakshmi K, Basit, Hajiraand, Jeanmonod, Rebecca. "Physiology, enstrual cycle." StatPearls, 2022, https://www.ncbi.nlm.nih.gov/books/NBK500020/.

Quaresma, C, Sparza,k PB. “Anatomy, Abdomen and Pelvis: Bartholin Gland. StatPearls, January 2024, https://www.ncbi.nlm.nih.gov/books/NBK557803/.