Emergency Use of Doxycycline

About doxycycline

Anthrax is a serious disease that you can get that comes from contact with infected animals or animal products. You can also get exposed to anthrax during a bioterrorism event. You can get sick if you breathe in anthrax spores, eat or drink contaminated products, or if the bacteria that causes anthrax enter the skin through a wound or sore. Anthrax is not contagious, so you can't get it from another person.

Doxycycline (DOX-i-SYE-kleen) is a prescription antibiotic approved by the Food and Drug Administration (FDA) to prevent anthrax.

Information on this page can also be found on a printable factsheet.

During an emergency

If you may be exposed to anthrax

In an anthrax emergency, public health authorities will provide guidance on who should get doxycycline to protect them if they may be or have been exposed to anthrax bacteria.

If you're told you're at risk, start taking the medicine as soon as possible after the emergency until public health officials or healthcare providers tell you to stop taking it. This guidance usually will be based on how likely it was that you were exposed to anthrax.

If you have been exposed to anthrax

If you were told you were might have been exposed to anthrax, take the medicine 2 times each day, 12 hours apart. To reduce your chance of getting sick, take the medicine as long as you are directed and do not stop taking it early. Most people will be given a 10-day supply to start, but you may have to take it for up to 60 days. Public health officials will tell you whether you need more and how to get it.

Tell your doctor if you are pregnant, become pregnant, or are breastfeeding while you're taking doxycycline.

For clinicians and public health authorities

Based on its scientific review, the FDA allows using certain lots of doxycycline even after the expiration date. For more information, go to the FDA website.

How to take doxycycline

• Take the medication for as long as it's directed, and don't skip doses.
  • Do not take 2 doses at once if you miss 1. Take the next dose when it's scheduled.

• Doxycycline works just as well whether you take it with or without food or milk.
  • Take it with food if you get an upset stomach when you take the medicine.

• Follow the doxycycline tablet crushing and mixing directions if you or your family members cannot swallow pills.

• Keep the pills dry. Store doxycycline pills and liquid at 68 to 77°F (20 to 25°C).

Adults and children 76 pounds (35kg) or more

• Take 1 pill (100 mg) in the morning with a full glass of water.
• Twelve (12) hours later, take 1 pill (100 mg) in the evening with a full glass of water.

Children under 76 pounds (35kg)

• Follow instructions provided on the liquid doxycycline label.
• Take the same amount in the morning and evening (12 hours apart) each day for as long as healthcare providers or officials recommend you should take it.
• Follow the directions for crushing and mixing if your child is prescribed a tablet but can't swallow a pill.

Interactions with other medicines

Talk to your doctor if you are on a blood thinner like warfarin or seizure medicine like phenytoin. Taking doxycycline may affect how much of these medicines you need to take.

Doxycycline can make birth control pills less effective. Use a second form of birth control until you finish taking all of your doxycycline.

Doxycycline might not work as well if you take it when you're on some other medicines. Take doxycycline at least 2 hours before or 2 hours after taking:

• Multivitamins, supplements or antacids with aluminum, calcium, iron, or magnesium
• Helidac, Kaopectate, Pepto-Bismol or other products with bismuth subsalicylate used for indigestion, nausea, or diarrhea

Side effects

Although there are potential side effects, the benefits of using doxycycline to prevent disease and death from anthrax exposure outweigh the risks.

Common side effects

Doxycycline can cause your skin to be more sensitive to the sun. Use sunscreen and cover exposed skin. Keep taking doxycycline even if you have some of the following side effects:

• Mild nausea
• Vomiting and/or diarrhea
• Mild sunburn
• Vaginal yeast infection

Serious side effects

Serious side effects from doxycycline are rare. They include:

• Closing of the throat or trouble breathing
• Swelling of the lips, tongue, or face
• Severe itching or rash, especially hives and wheals (red, swollen bumps on the skin)
• Severe stomach cramps with fever or bloody or watery diarrhea
• Yellowing of the eyes or skin, or dark brown or tea-colored urine (jaundice)
• Pain when swallowing (esophageal ulcers)
• Unusual bleeding or bruising
• Severe headaches, dizziness, or double vision

You should stop taking doxycycline and talk to your doctor right away if you experience these symptoms.

Long-term side effects

If children take doxycycline for more than 21 days, there are some additional risks. However, in an anthrax emergency, your healthcare provider may decide that the benefits outweigh the risks:

• Slowed bone growth in children.
• Discolored teeth or poor tooth enamel in children under 8 years or in infants whose mothers took doxycycline during the last half of pregnancy or while nursing

Alternatives to doxycycline

Public health officials will tell you if other antibiotics (such as ciprofloxacin, levofloxacin, or amoxicillin) are available. Talk to public health officials or healthcare providers if you cannot take doxycycline.

Countermeasures Injury Compensation Program

In the rare event that doxycycline causes serious problems, you may be eligible to receive help with medical costs. A federal program may help cover medical costs for those severely affected by certain medicines or vaccines. Learn more about the Countermeasures Injury Compensation Program or call 1-855-266-2427.