A third nipple (also called supernumerary nipples, in the case of multiple nipples) is a condition in which you have one or more extra nipples on your body. This is in addition to the two typical nipples on the breasts.

The third nipple, or the presence of multiple nipples, is also known as polymastia or polythelia. It’s not certain how many have this condition. According to the Genetic and Rare Diseases Information Center (GARD), it is a rare condition. It’s estimated that about 200,000 Americans have one or more extra nipples (less than half a percent of people in the United States). They’re also more common in men than in women.

While a third nipple is the most common number of extra nipples people with this condition have, it’s possible to have up to eight supernumerary nipples.

A third or supernumerary nipple is usually not as fully developed as a regular nipple. You may not even be able to recognize an extra nipple right away. Some appear simply as tiny bumps with no familiar features of a nipple, but others can look just like a regular nipple at first glance.

Third nipples most commonly happen on the “milk line.” This refers to the area on the front of your body that starts in your armpit and goes down through and past your nipples to your genital area. This is the easiest way to tell the difference between an extra nipple and a mole or birthmark. Moles and birthmarks also tend to be flat and not have any ridged or nipple-like bumps in them.

But not all extra nipples may appear here. They can appear almost anywhere on your body, even on your hands or feet. These are known as ectopic supernumerary nipples.

Supernumerary nipples can fall into several different categories depending on their size, shape, and tissue makeup:

  • Category One (polymastia): The extra nipple has an areola around it (the soft, circular tissue around a nipple) and typical breast tissue underneath, which means that a full breast has developed.
  • Category Two: The extra nipple has breast tissue underneath but no areola is present.
  • Category Three: The extra nipple area has breast tissue underneath but no nipple is present.
  • Category Four: The extra nipple has breast tissue underneath but no nipple or areola is present.
  • Category Five (pseudomamma): The extra nipple has an areola around it but only has fat tissue underneath rather than breast tissue.
  • Category Six (polythelia): The extra nipple appears by itself with no areola or breast tissue underneath.

Third nipples develop while a human embryo is developing in the womb.

During the fourth week of pregnancy, the embryo’s two milk lines, which are made of ridged ectoderm tissue (a type of tissue that eventually becomes part of your skin), thicken.

Normally, the milk line tissue stays thick and forms your nipples while the rest of the thickened skin softens up again. But in some cases, parts of the milk line ridges don’t become regular ectoderm tissue again. When this happens, supernumerary nipples can appear where the milk tissue stayed thick and ridged after birth and development into adulthood.

You usually don’t need to have a third nipple removal for health reasons. Supernumerary nipples don’t indicate any underlying conditions or cause any conditions themselves. But you may want to get them removed because you don’t like the way they look or for other cosmetic reasons. Supernumerary nipples can also lactate in both men and women, especially if they’re more fully developed.

A quick, noninvasive outpatient surgery can be performed to remove extra nipples with minimal pain and recovery time. A nipple removal surgery can cost as low as a $40 copay depending on your insurance. Some practices may charge up to $500 or more for the surgery.

In rare cases, a third nipple can be a sign of a congenital breast defect or an early sign of a malignant growth or tumor. One of the genes that can cause an extra nipple, called Scaramanga’s gene, can also make it possible for an extra nipple to get breast cancer, just like a regular breast.

Certain types of extra nipples, such as polythelia (category six), can be related to kidney conditions like end-stage renal disease or cancer of the kidney cells.

See your doctor if you have an extra nipple that’s causing you discomfort because it’s lactating or radiating pain to find out if any treatments or surgery options are right for you. See your doctor as soon as possible if an extra nipple forms any new lumps, hard tissue, or a rash over the area. A doctor should examine your extra nipple if any abnormal discharge leaks from the nipple.

Get regular physicals so that your doctor can monitor the condition of any extra nipples. This allows your doctor to look for any signs of abnormal growths or activity in or around the supernumerary nipple tissue. Catching any tumors or tissue abnormalities early can limit any risks of developing cancer.

Supernumerary nipples are usually not a cause for concern. In some cases, an extra nipple may indicate an underlying condition, including tumor growth or cancer. But sometimes you may never even know you have one. Pregnant and breastfeeding women often discover extra nipple tissue as they react to hormones.

Getting regular physicals and letting your doctor know that you have extra nipples can help prevent any possible complications.

A third nipple, also known as a supernumerary nipple, is the presence of one or more extra nipples on the body. They commonly appear in the “milk line,” the front area of the body from the armpit to the genitals. Third nipples usually aren’t a health risk, and a quick surgery can remove them.