If you split your lip as a result of trauma, you may have a fat lip until the swelling goes down. Inspect it closely if it is the result of a fall, because debris in the wound could cause an infection. It should heal naturally, and if the split is not extremely deep -- or if you need sutures -- it should not leave a scar. If you have dry, chapped lips, keep your split lip moisturised with a balm while it is healing.
Apply pressure against the split lip with a clean, dry washcloth or small towel to stop the bleeding. Hold it against the lip for about five minutes, or until the cut no longer bleeds after the towel is taken away.
Clean the split lip with soapy water and a soft washcloth. Rinse it with clear water.
Prepare a solution of equal parts water and hydrogen peroxide in a small bowl. Soak a cotton ball in the hydrogen peroxide solution and apply it to the wound by gently pressing it against the area. Spit out any hydrogen peroxide that should happen to drip inside your mouth.
Examine the wound. If it gapes, seems to be deep or goes past the line where the lip meets the skin, you may need stitches to close the wound, and possibly an antibiotic to prevent infection. If the bleeding does not stop, it will most likely need stitches. Call your doctor or head to the nearest hospital or urgent care facility.
Apply a cold compress, such as a few pieces of ice wrapped in a washcloth, to the injured site if swelling is present. Keep it on for 10 minutes, take it off for 10 minutes, then reapply. This will help to keep the swelling down.
Take over-the-counter pain relievers, such as acetaminophen or ibuprofen, if you are in pain.
See a medical professional if you see signs of infection such as redness, pus, tenderness or fever.
The hydrogen peroxide solution may burn. A little fizzing reaction is normal. Avoid any salty or citrus foods that might sting.