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Doxycycline (Tetracycline, Antibiotic Agent)

Written by Stephanie Nera, RPh, PharmD · Pharmacology

Updated Aug 21, 2022

Doxycycline (Tetracycline, Antibiotic Agent)

Doxycycline is a tetracycline-type antibiotic that stops the growth of bacteria. It treats a wide variety of infections and diseases. Doxycycline is only effective against bacterial infections, not viral infections. All antibiotics are only available with a doctor’s prescription.


Know the basics

What is doxycycline used for?

How should I take doxycycline?

For oral tablets or capsules, swallow the dose whole without chewing or crushing it. Take it with or without food. Do not eat or drink food that contains iron, calcium, or other similar minerals (e.g. milk, dairy products).

Parenteral (e.g. IV) dosage forms should be administered by licensed healthcare professionals.

How do I store doxycycline?

This product is best stored at room temperature away from direct light and moisture. To prevent drug damage, you should not store it in the bathroom or the freezer. 

There may be different brands of this drug that may have different storage needs. So, it is important to always check the product package for instructions on storage, or ask your pharmacist. For safety, you should keep all medicines away from children and pets.

You should not flush this product down the toilet or pour them into a drain unless instructed to do so. Additionally, it is important to properly discard this product when it is expired or no longer needed. Consult your pharmacist for more details about how to safely discard your product.

Know the precautions & warnings

What should I know before using doxycycline?

Before using this drug, tell your doctor if you are/have:

  • Pregnant or breastfeeding.
  • Receiving a live vaccine.
  • Taking any other medicines. This includes any prescription, OTC, and herbal remedies.
  • An allergy to any of the ingredients of this product.
  • Any other illnesses, disorders, or medical conditions.

Is it safe to take doxycycline during pregnancy or breast-feeding?

Doxycycline is pregnancy risk category D according to the US Food and Drug Administration (FDA). There is evidence that tetracyclines, like doxycycline, can affect the growth of fetuses and young children. Do not take this medication unless your doctor prescribes it.

FDA pregnancy risk category reference below:

  • A=No risk
  • B=No risk in some studies
  • C=There may be some risk
  • D=Positive evidence of risk
  • X=Contraindicated
  • N=Unknown

Know the side effects

What are the side effects of doxycycline?

Like all drugs, this product may have side effects. If they occur, side effects are generally mild and resolve once treatment is finished or the dose is lowered. Some reported side effects include:

  • Allergic reaction
  • Diarrhea
  • Nausea, vomiting
  • Abdominal pain
  • Headache
  • Tinnitus
  • Jaundice
  • Blood abnormalities
  • Muscle or joint pain
  • Vision disturbances
  • Skin hyperpigmentation
  • Photosensitivity

Seek medical attention if you experience these potentially fatal effects:

  • Anaphylactic reactions
  • Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN)
  • Clostridium difficile-associated disease

However, not everyone experiences these side effects. In addition, some people may experience other side effects. So, if you have any concerns about a side effect, please consult your doctor or pharmacist.

Know the interactions

What drugs may interact with doxycycline?

This medication may interact with other drugs that you are currently taking, which can change how your drug works or increase your risk for serious side effects. 

To avoid any potential drug interactions, you should keep a list of all the drugs you are using (including prescription drugs, nonprescription drugs, and herbal products) and share it with your doctor and pharmacist. 

Drugs with known interactions:

  • Isotretinoin
  • Oral contraceptives
  • Anticoagulants
  • Antacids or supplements that contain aluminum, calcium, magnesium, zinc, or iron
  • Bismuth preparations
  • Carbamazepine
  • Phenobarbital
  • Phenytoin
  • Primidone
  • Ciclosporin
  • Penicillin
  • Rifampicin
  • Methoxyflurane

If you experience an adverse drug interaction, inform your doctor immediately to reevaluate your treatment plan. Approaches include dose adjustment, drug substitution, or ending therapy.

Does food or alcohol interact with doxycycline?

This drug may interact with food or alcohol by altering the way the drug works or increase the risk for serious side effects. Do not eat food that is rich in iron or calcium, as it can bind with doxycycline and reduce its availability. Avoid drinking alcohol as it can decrease its half-life. Also, avoid drinking caffeine.

Please discuss with your doctor or pharmacist any potential food or alcohol interactions before using this drug.

What health conditions may interact with doxycycline?

This drug may interact with underlying conditions. This interaction may worsen your health condition or alter the way the drug works. Therefore, it is important to always let your doctor and pharmacist know all the health conditions you currently have, especially:

Understand the dosage

The information provided is not a substitute for any medical advice. Therefore, you should always consult with your doctor or pharmacist before using any medication.

What is the dose for an adult?

The usual dose of oral doxycycline is 200 mg on the first day of treatment (administered 100 mg every 12 hours or 50 mg every 6 hours) followed by a maintenance dose of 100 mg/day.

The maintenance dose may be administered as a single dose or as 50 mg every 12 hours. In the management of more severe infections (particularly chronic infections of the urinary tract), 100 mg every 12 hours is recommended.

  • Uncomplicated gonococcal infections in adults (except anorectal infections in men): 100 mg, by mouth, twice a day for 7 days. As an alternate single visit dose, administer 300 mg stat followed in one hour by a second 300 mg dose.
  • Acute epididymo-orchitis caused by gonorrhoeae: 100 mg, by mouth, twice a day for at least 10 days.
  • Primary and secondary syphilis: 300 mg a day in divided doses for at least 10 days.
  • Uncomplicated urethral, endocervical, or rectal infection in adults caused by Chlamydia trachomatis: 100 mg, by mouth, twice a day for at least 7 days.
  • Nongonococcal urethritis caused by trachomatis and U. urealyticum: 100 mg, by mouth, twice a day for at least 7 days.
  • Acute epididymo-orchitis caused by C. trachomatis: 100 mg, by mouth, twice a day for at least 10 days.
  • Inhalational anthrax (post-exposure): ADULTS: 100 mg of doxycycline, by mouth, twice a day for 60 days. 
  • When used in streptococcal infections, therapy should be continued for 10 days.

What is the dose for a child?

The recommended dosage schedule for pediatric patients (>8years old,

How is doxycycline available?

Doxycycline is available in the following dosage forms and strengths:

  • Capsule: 40 mg, 50 mg, 75 mg, 100 mg, 150 mg
  • Solution for injection: 100mg
  • Suspension for reconstitution: 25mg/5mL, 
  • Syrup: 50mg/5mL, 
  • Tablet: 75 mg, 75 mg, 80 mg, 100 mg, 150 mg, 200 mg

What should I do in case of an emergency or overdose?

In case of an emergency or an overdose, call your local emergency services or go to the nearest emergency room.

What should I do if I miss a dose?

If you miss a dose, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and take your regular dose as scheduled. Do not take a double dose. Avoid missing any doses of antibiotics to prevent antibiotic resistance and treatment failure.


Hello Health Group does not provide medical advice, diagnosis or treatment.

Written by

Stephanie Nera, RPh, PharmD


Updated Aug 21, 2022

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