Doxycycline is used to treat a wide variety of bacterial infections. This medication is known as a tetracycline antibiotic. It works by stopping the growth of bacteria.

This section contains uses of this drug that are not listed in the approved professional labeling for the drug but that may be prescribed by your health care professional. Use this drug for a condition that is listed in this section only if it has been so prescribed by your health care professional.

This medication may also be used to control the build-up of fluid around the lungs (pleural effusion) caused by tumors that have spread to the lungs. For this condition, doxycycline is placed in the space around the lungs through a chest tube.

This medication is given by injection into a vein as directed by your doctor, usually once or twice daily. It should be injected slowly over at least 1 hour (usual range is 1 to 4 hours). The dosage is based on your medical condition and response to treatment. Children's dosage is also based on weight.

If you are giving this medication to yourself at home, learn all preparation and usage instructions from your health care professional. Before using, check this product for particles or discoloration. If either is present, do not use the liquid. Learn how to store and discard medical supplies safely.

For the best effect, use this antibiotic at evenly spaced times. To help you remember, use this medication at the same time(s) every day.

Continue to use this medication for the full time prescribed, even if symptoms disappear after a few days. Stopping the medication too early may result in a return of the infection.

Tell your doctor if your condition lasts or gets worse.

Diarrhea, loss of appetite, nausea, vomiting, headache, or rectal discomfort may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly.

Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor right away if you have serious side effects such as:

• nausea/vomiting that doesn't stop
• signs of kidney problems (such as change in the amount of urine)
• unusual tiredness
• redness/swelling/pain at the injection site
• weakness
• hearing changes (such as ringing in the ears, decreased hearing)
• stomach/abdominal pain

Tetracycline drugs such as doxycycline may rarely cause increased pressure around the brain (intracranial hypertension-IH). The risk of this side effect is greater for women of childbearing age who are overweight or who have had IH in the past. If IH develops, it usually goes away after doxycycline is stopped; however, there is a chance of permanent vision loss or blindness. Get medical help right away if you have:

• nausea/vomiting that doesn't stop
• headache that is severe or doesn't stop
• vision changes (such as blurred/double vision, decreased vision, sudden blindness)

This medication may rarely cause a severe intestinal condition due to a bacteria called C. difficile. This condition may occur during treatment or weeks to months after treatment has stopped. Tell your doctor right away if you develop:

• diarrhea that doesn't stop
• abdominal or stomach pain/cramping
• blood/mucus in your stool

If you have these symptoms, do not use anti-diarrhea or opioid products because they may make symptoms worse.

Use of this medication for prolonged or repeated periods may result in oral thrush or a new vaginal yeast infection. Contact your doctor if you notice white patches in your mouth, a change in vaginal discharge, or other new symptoms.

A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including:

• fever that doesn't go away
• new or worsening lymph node swelling
• rash
• itching/swelling (especially of the face/tongue/throat)
• severe dizziness
• trouble breathing

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

See also Side Effects section.

Before using doxycycline, tell your doctor or pharmacist if you are allergic to it; or to other tetracycline medication (such as minocycline, tetracycline); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of:

• liver disease
• lupus

Doxycycline may cause live bacterial vaccines (such as typhoid vaccine) to not work well. Tell your health care professional that you are using doxycycline before having any immunizations/vaccinations.

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Children younger than 8 years may be more sensitive to the side effects of doxycycline, especially tooth discoloration. Tooth discoloration has also occurred in older children and young adults. Discuss the risks and benefits of this medication with the doctor.

Tell your doctor if you are pregnant or plan to become pregnant. You should not become pregnant while using doxycycline. Doxycycline may harm an unborn baby. If you become pregnant, talk to your doctor right away about the risks and benefits of this medication.

This medication passes into breast milk. Consult your doctor before breastfeeding.

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

Some products that may interact with this drug include:

• anti-seizure medications (such as phenytoin)
• retinoid medications taken by mouth (such as acitretin, isotretinoin)
• digoxin
• phenobarbital
• warfarin

This medication may interfere with certain lab tests (such as some urine tests for sugar), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call 1-800-222-1222. Canada residents can call 1-844-764-7669.

If you are using this drug for a long time, lab and/or medical tests (such as complete blood count, kidney/liver function) should be done while you are using this medication. Keep all medical and lab appointments. Consult your doctor for more details.

It is important to get each dose of this medication as scheduled. If you miss a dose, ask your doctor or pharmacist right away for a new dosing schedule. Do not double the dose to catch up.

Consult the product instructions and your pharmacist for storage details. Keep all medications away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company.