Rats can bite when they feel cornered or pressured. This may happen when you put your hand inside of a rat cage or come across one in the wild.

They’re more common than they used to be. This is partly because more people are keeping them as pets. Plus, the number of rats in the United States in general is growing, thanks to climate change.

Rat bites aren’t always serious, but they can become infected or cause a condition called rat-bite fever.

Read on to learn more about rat bites, including how to identify them and when it’s time to see a doctor.

Rat bites usually look like a small, single puncture wound or a number of small cuts. They also tend to bleed and cause painful swelling. If the bite becomes infected, you might also notice some pus.

Rat-bite fever (RBF), as its name suggests, is a condition that can develop following a rat bite. Bites from squirrels, mice, weasels, and cats can also cause rat-bite fever, though not as often as rat bites.

In many cases, rat-bite fever causes a rash. This rash may be flat or have little bumps and can range in color from red to purple. It sometimes resembles bruising

There are two types of rat-bite fever, each caused by different bacteria. Streptobacillary rat-bite fever is the more common type in North America, while spirillary rat-bite fever (also called Sodoku) is more common in Asia.

Symptoms of streptobacillary RBF

Bites that cause streptobacillary RBF usually heal relatively fast.

However, in some cases, you may experience the following symptoms within 3 to 10 days:

  • joint pain
  • fever and chills
  • muscle pain
  • headache
  • skin rash
  • vomiting and diarrhea

Symptoms of spirillary RBF

A bite that causes spirillary RBF might look like it’s healing quickly. However, the following symptoms can pop up within one to three weeks after the bite:

  • headache
  • fever and chills
  • muscle pain
  • sore throat and vomiting
  • swelling of lymph nodes
  • ulcer at the wound
  • skin rash

If you have a rat bite, wash the area with warm water and soap as soon as possible. Dry the area with a clean towel and apply an antibiotic ointment. Cover with a clean bandage.

Even if the bite seems minor, it’s best to see a doctor as soon as possible. Rat bites are prone to turning into potentially serious infections. You should also get a tetanus shot, especially if it’s been more than five years since your last one (or you don’t remember the date of your last tetanus shot).

In some cases, you might also be prescribed antibiotics to stay ahead of any potential infection

As the bite heals, keep an eye out for any signs of rat-bite fever or infection, such as:

  • skin that’s warm to the touch
  • redness and welling
  • pus
  • throbbing pain
  • fever and chills
  • joint pain

Treating rat-bite fever or infection

If you do develop rat-bite fever or an infection, you’ll need antibiotics. You’ll need to take the antibiotic for 7 to 10 days. For more severe bites, you may need intravenous antibiotics.


Make sure you take the full course of antibiotics as prescribed by your doctor, even if you start to feel better before finishing them. Otherwise, you may not kill all of the bacteria, which can make them resistant to antibiotics.

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Rat-bite fever and infected bites usually respond well to a standard course of antibiotics. But rat-bite fever can cause some lingering fatigue, joint pain, or a rash.

Left untreated, rat-bite fever and infections can cause serious health problems.

These include:

Some of these complications are life-threatening, so it’s important to seek immediate treatment for any bite that’s accompanied by unusual symptoms.

Whether you see rats as lovable pets or a nuisance to be avoided, you should always see a doctor if you’ve been bitten by one. With quick treatment, you can avoid rat-bite fever or an infection.

If you do develop a fever or infection, you’ll likely be on the mend after a week of antibiotics. Just make sure you take the full course of antibiotics as prescribed by your doctor.

In some cases, you might still have a slight fever or joint pain after a bout of rat-bite fever. These symptoms will eventually go away over time.