Anthrax Emergency: How to Take Ciprofloxacin to Prevent Anthrax

Emergency Use Instructions for Recipients

During an anthrax emergency, you will be given a medicine called ciprofloxacin (sip-roe-FLOX-a-sin) because you may have breathed in anthrax germs. These germs can be deadly. Taking this medicine reduces your chance of getting sick and dying. Until officials know for sure who breathed in the germs, it is important to start taking this medicine as soon as possible after the emergency starts. Public health officials will provide information on who should get the medicine. If you have questions, talk to a doctor or healthcare provider about taking ciprofloxacin.

People who may have breathed in anthrax germs should take this medicine twice a day for 60 days. Most people will be given a 10-day supply to start. Public health officials will tell you whether you need more and how to get it. To reduce your chance of getting sick, take the medicine as long as you are directed and avoid stopping early.

What is anthrax?

Anthrax is a serious disease that can be deadly. You can get sick if you breathe in the anthrax germs. You cannot get anthrax from another person who has anthrax.

  • Early on, you could have any of the following symptoms: fever, chills, tiredness, cough or headache.
  • Later, you could develop shortness of breath, chest discomfort, confusion or nausea. Symptoms usually start within 7 days of breathing in anthrax germs, but can start within 24 hours or take up to 6 to 7 weeks to appear. See a doctor right away if you have symptoms. If you take ciprofloxacin as directed and begin to feel sick anyway or show any of the symptoms mentioned above, get medical care right away.

What is ciprofloxacin?

Ciprofloxacin is a prescription antibiotic approved by the Food and Drug Administration (FDA) to prevent anthrax. FDA is allowing certain uses of ciprofloxacin, including its use without a prescription, during an anthrax emergency. If you were given ciprofloxacin with an expired date on the container, please note that FDA is allowing the use of certain lots of ciprofloxacin beyond the expiration date on the container based on FDA’s scientific review. For more information, go to the FDA website at www.fda.govexternal icon (search for “ciprofloxacin expiration”).

Who should NOT take ciprofloxacin?

Do not take ciprofloxacin if you have had a severe allergic reaction to ciprofloxacin or similar medicines known as quinolones. A severe reaction may include closing of the throat, trouble breathing, or swelling of the lips, tongue or face. Avoid taking ciprofloxacin if you have a history of myasthenia gravis or are taking Zanaflex (tizanidine). Talk to your doctor or public health official about other medicines available to prevent anthrax.

How do I take ciprofloxacin?

  • For children who weigh 67 pounds (31 kg) or more and adults aged 18 years or older:
    • Take 1 pill (500 mg) in the morning with a full glass of water (with or without food) and
    • Take 1 pill (500 mg) in the evening with a full glass of water (with or without food)
      • The morning and evening doses should be taken 12 hours apart each day for as long as directed.
      • If you have trouble swallowing pills, please talk to your doctor for advice or an alternative medicine.
  • Children weighing less than 67 pounds (31 kg), the dose is determined based on weight:
    • Follow instructions provided on the liquid ciprofloxacin label.
    • Take the same amount in the morning and in the evening (12 hours apart) each day as long as directed. Shake the liquid very well for about 15 seconds before each use.
  • Do not skip doses. However, if you miss a dose, do NOT take 2 doses at once. Take the next dose as scheduled.
  • If you have severe kidney disease, you may need a dose change. Talk to a doctor.
  • Do not split, crush or chew the pills.
  • Do not take ciprofloxacin with milk, yogurt or calcium-fortified juices.
  • Keep the pills dry. Store ciprofloxacin pills and liquid at room temperature (between 68–77°F or 20–25°C). The liquid can be stored for up to 14 days at room temperature.
  • Keep ciprofloxacin away from children and pets. Call the poison control center if children or pets ingest the medicine by accident (1-800-222-1222).

What are common side effects of ciprofloxacin?

KEEP taking ciprofloxacin if you have mild nausea, vomiting and/or diarrhea, a mild sunburn or a vaginal yeast infection. If these symptoms become severe, talk to your doctor.

What are possible serious side effects of ciprofloxacin?

Serious side effects from ciprofloxacin are rare. STOP taking ciprofloxacin and get medical care right away (go to the emergency room or call 911) if you have:

  • Closing of the throat or trouble breathing
  • Swelling of the lips, tongue or face
  • Severe itching or rash, especially hives or wheals (red, swollen bumps on the skin)
  • Pain, swelling or inflammation of joints or tendons
  • Seizures, dizziness, tremors or serious mood changes
  • Very fast or irregular heart beat
  • Severe stomach cramps with fever or bloody or watery diarrhea
  • Pain, burning, tingling, numbness or weakness of your arms, hands, legs or feet
  • Yellowing of eyes or skin or dark brown or tea-colored urine
  • Unusual bleeding or bruising

What if I am taking other medicines?

  • If you take Zanaflex (tizanidine), a medicine for muscle spasms, it is important to talk with your doctor right away. A change in medicine for muscle spasms or medicine to prevent anthrax would be necessary since tizanidine and ciprofloxacin should not be used together.
  • Talk to your doctor if you take any of the following medicines: a blood thinner like warfarin, an anti-diabetic medicine like glyburide, phenytoin for seizures, theophylline for asthma or clozapine for schizophrenia. Ciprofloxacin may affect how much of these medicines you need.
  • Ciprofloxacin might not work as well when taken with some medicines. Take it at least 2 hours before or 6 hours after taking:
    • Antacids
    • Carafate (sucralfate)
    • Videx (didanosine)
    • Multivitamins or supplements with magnesium, calcium, aluminum, iron or zinc
    • Phosphate binders

What else do I need to know about ciprofloxacin?

  • It can worsen muscle weakness or breathing problems in myasthenia gravis. Talk to your doctor if you have a history of myasthenia gravis disorder.
  • It can cause your skin to be more sensitive to the sun. Use sunscreen and cover exposed skin.
  • It can make you feel jittery if you drink coffee, caffeinated sodas or energy drinks. Drink less caffeine if this occurs.
  • Tell your doctor if you are or become pregnant or are breastfeeding.
  • On rare occasions, ciprofloxacin can cause serious problems. A federal program called the Countermeasures Injury Compensation Program (CICP) may help pay for costs of medical care and other specific expenses of certain people who have been seriously injured by some medicines or vaccines. If you have been injured by ciprofloxacin used to prevent anthrax, you can learn more about this Program by visiting icon or by calling 1-855-266-2427 (toll-free).

What other antibiotics can I take instead of ciprofloxacin?

Public health officials will tell you if other antibiotics (such as doxycycline, levofloxacin or amoxicillin) are available. The risks and benefits of other available antibiotics will be explained in separate instructions.

Risk-Benefit Statement

Although ciprofloxacin has some potential and serious side effects, the expected benefit of ciprofloxacin in helping to prevent disease and death associated with anthrax exposure outweighs these risks.

How do I report side effects or medication errors?

Tell your doctor or healthcare provider right away and report side effects or medication errors to MedWatchexternal icon or 1-800-FDA-1088.

Note: Ciprofloxacin EUI for Recipients (originally issued 03/28/2016; revised 08/18/2017)