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If you have mild to moderate Crohn's, your doctor may give you antibiotics to help keep your disease under control.

You may need to take the antibiotics even after you feel better to keep your Crohn's from getting worse again.

There are two ways antibiotics treat the inflammation in your gut from Crohn's. Researchers believe antibiotics may help control symptoms by reducing bacteria levels in your intestine and by curbing the intestine's immune system.

You will also get them to treat specific infections and complications.

Antibiotics for Crohn's Complications

Abscesses. These are pockets of pus that in Crohn’s often develop near the anus.

Fistulas. These are abnormal tunnels that go from one part of your intestine to another or to nearby areas, such as the bladder, vagina, anus, or skin.

Pouchitis. For some people, Crohn’s disease is so severe that they need an operation to have their colon removed. The surgeon makes an internal pouch to hold solid waste before it leaves your body. If this area becomes inflamed -- known as "pouchitis" -- you will need antibiotics for treatment.

Antibiotics for Crohn's Disease

The most common antibiotics used for Crohn's disease are:

  • Cipro (ciprofloxacin)
  • Flagyl (metronidazole)

Some people need to get antibiotics through a vein (IV).

Side Effects of Antibiotics

Side effects of metronidazole may include:

  • Nausea
  • Loss of appetite
  • Metallic taste
  • Diarrhea
  • Dizziness
  • Headaches
  • Dark urine

Side effects are more common at higher doses.

With metronidazole, you may also have numbness or tingling in your hands. If you do, you will need to stop taking it. Although this side effect is rare, sometimes it does not go away.

Avoid alcohol if you are taking metronidazole. It can interact with the drug to cause a rare, but severe, reaction. The symptoms are nausea, vomiting, and shortness of breath.

These side effects of ciprofloxacin are rare, but may include:

  • Headache
  • Nausea
  • Sensitivity to sun
  • Rupture of a tendon (very rare)

You are also at greater risk for a severe type of colitis. If you get it, you will need treatment with another type of antibiotic.

Do not take ciprofloxacin within a couple of hours of taking:

  • Antacids such as Tums or Rolaids
  • Vitamin or mineral supplements that contain calcium, iron, or zinc

This combination can make the antibiotic less effective.

Other Precautions

No matter which antibiotic you are taking:

  • Let your doctor know if you are pregnant before starting the medication.
  • Avoid sun exposure. Wear sunscreen during daylight hours.
  • Know that antibiotics can make birth control pills less effective.
  • Be aware that antibiotics can make bleeding more likely if you are also taking anticoagulants (drugs that curb blood clots).