Doctors categorize burns into three categories:

First-Degree Burn

These only affect the outermost layer of skin and can be caused by sunburns, scalds, and electricity. While they are the least serious, they can result in skin redness, mild pain and swelling, and skin peeling. Some of them can be large and painful, however, and may require a trip to the doctor, especially if they are electrical burns. Electrical burns can affect more of the skin than you can see, so seeing a physician is of particular importance.

Second-Degree Burn

Affects the outer layer of skin and the layer just underneath. These are more serious because more than just a superficial layer of skin is damaged. This kind of burn can cause the skin to blister and become extremely red and sore. These wounds are also prone to infection, so they need to be kept clean and bandaged properly. The more severe the blisters are, the longer they will take to heal.

However, these burns usually heal within two to three weeks but can often cause pigment changes to the skin. Occasionally, the injury is severe enough to require skin grafting, which is removing healthy skin from another area of the body to place over the site of the burned skin.

Third-Degree Burns

Third-degree burns are the second-most severe. They destroy or damage the deepest layer of skin. People mistake this type of damage for the most painful; however, with third-degree burns, the damage can be so extensive the nerves have completely died, which means there’s no pain or sensation at all in the burned area. These injuries typically heal with severe scarring and contracture (hardening of muscles, tendons, or other tissues) if no surgery is involved.

With surgery, however, there is more chance your skin can recover with less scarring. Third-degree burns also come with increased risk for complications, such as blood loss, infections, and shock. These burns can allow bacteria to enter through the broken skin, which could result in sepsis or tetanus. Hypothermia and hypovolemia are also dangers with these types of burns because the skin isn’t preventing the body from losing heat and the burn could cause too much blood loss.

Fourth-Degree Burns

Fourth-degree burns are the worst types because they extend through the entire skin and into underlying fat, muscle, and bone. The skin will be so severely damaged it will look black and charred with eschar (dead tissue). The wound will be painless because the nerves have been destroyed. However, there is no treatment for this type of burn. It will require excision or amputation to remove the affected area from the rest of the body. These burns can also be so severe they cause death