What Is an Ulcer?

Medically Reviewed by Debra Jaliman, MD on March 03, 2021
5 min read

Ulcers are sores that are slow to heal or keep returning. They can take many forms and can appear both on the inside and the outside of your body.

They can be found on places of your body you can see, such as a leg ulcer found on the skin, or in places you can’t see, such as a peptic ulcer in the lining of your stomach or upper intestine. From your eye to your foot, you can get them just about anywhere on your body.

Injuries, diseases, and infections can cause them. What they look like depends on where you have them and how you got them. While some go away on their own, others cause serious problems if you don’t treat them.

These can be painful and may take months to heal. They vary in how they look, from red splotches that ooze to darkened patches of swollen skin.

What causes them? Most start with an injury that doesn’t heal well because of some other health issue -- usually, a blood flow problem.

If you have problems with your veins, you can get venous ulcers, the most common kind on your legs. You’re more likely to get them if you have:

If you have problems with your arteries, such as plaque buildup (atherosclerosis), you may get arterial ulcers. Typically, you get these on your feet and toes.

Diabetes can cause nerve and blood flow problems that lead to ulcers. They usually show up on your feet. When you have diabetes, it’s best to check your feet for even minor injuries every day.

What problems can they lead to? If untreated, leg and foot ulcers can lead to:

  • Infection
  • Having a foot or part of your leg removed (sometimes a problem with diabetic ulcers)
  • Osteoporosis (when your bones become weak and easily break in a fall)

Also called pressure ulcers or pressure sores, at first they just look like off-color skin. Over time though, they can grow into deep, open wounds.

What causes them? You get bedsores when prolonged pressure on your skin leads to blood flow problems. You’re more likely to get them if you have a condition that makes it hard for you to move and you’re forced to lie down or sit most of the time. An example is when you’ve had surgery that requires bed rest for a long time.

What problems can they lead to? Bedsores can cause:

  • Bone and joint infections
  • Cancer in your skin’s upper layers
  • Cellulitis, a painful infection in your skin and soft tissue
  • Flesh-eating bacteria (necrotizing fasciitis), a life-threatening infection
  • Sepsis, a life-threatening problem where bacteria get into your blood and move throughout your body

These are painful sores on the penis, vagina, or anus.

What causes them? They’re usually caused by sexually transmitted diseases such as herpes, syphilis, and chancroid (in which bacteria cause skin ulcers to form, usually on the genitals). They may also be caused by an injury or a reaction to a skin care product.

What problems can they lead to? Open sores on your genitals make you more likely to give or get sexually transmitted diseases (STDs), including HIV.

These show up on the cornea, which is the surface of your eye. They may cause redness and pain, and you may feel like you have something stuck in your eye.

What causes them? Typically, you get a corneal ulcer from an infection. You might also get it because of dry-eye syndrome, an injury to your cornea, or problems with your eyelids which can cause your corneas to dry out and form ulcers.

What problems can they lead to? They can cause serious vision problems, including blindness. If you think you have one, it’s best to get treatment right away.

One type of ulcer you can’t see is a peptic ulcer. You can get them in your stomach or the upper part of your small intestine. For most people, stomach pain is the first clue they have one.

What causes them? Normally, you have just the right amount of stomach acid to break down your food. But if something throws your stomach off, the acid can eat away at its lining and cause an ulcer. This can happen because of:

What problems can they lead to? If not treated, peptic ulcers can cause:

  • Bleeding inside your body
  • Blockages that keep food from moving out of your stomach
  • Infection

Also called canker sores, these small, round sores may be red, yellow, or gray. They show up inside your cheeks and lips, as well as on your tongue and gums. They’re different from cold sores that you may get around the outside of your mouth.

What causes them? Certain conditions, such as celiac disease (an immune reaction eating gluten) or Crohn’s (a bowel disease that causes inflammation), can give you mouth ulcers. They can also be caused by trauma, sensitivity to foods with lots of acid, changes in your hormone levels, or not enough vitamins.

What problems can they lead to? Usually, mouth ulcers are harmless and go away on their own. Check with your doctor if they last more than 3 weeks, you keep getting them, or they get redder and more painful.