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What is doxycycline?

Doxycycline is a tetracycline-derived antibiotic used to treat various bacterial infections within the body. It is considered broad-spectrum because it is effective against a range of bacteria types. It’s also used to treat acne and may be prescribed to prevent malaria.¹ ²

What is doxycycline used to treat?

More specifically, doxycycline has been approved by the US Food and Drug Administration (FDA) for the treatment of the following infections (some indicated only when testing shows susceptibility or when doxycycline is needed as an alternative to penicillin):

  • Specific bacterial infections (Yersinia pestis, Francisella tularensis, Vibrio cholerae, Brucella, Bartonella bacilliformis, Listeria monocytogenes, Fusobacterium, Clostridium, Actinomyces israelii, and susceptible infections caused by Escherichia coli, Enterobacter aerogenes, Shigella, Acinetobacter, Fusobacterium fusiforme, Campylobacter fetus)

  • Certain sexually transmitted infections (Chlamydia trachomatis, granuloma inguinale caused by Klebsiella granulomatis, chancroid caused by Haemophilus ducreyi, syphilis, uncomplicated gonorrhea)

  • Specific respiratory tract infections (Mycoplasma pneumoniae, Haemophilus influenzae, Klebsiella species, Streptococcus pneumoniae, Chlamydophila psittaci)

  • Urinary tract infections caused by Klebsiella granulomatis, nongonococcal urethritis caused by Ureaplasma urealyticum

  • Certain ophthalmic infections caused by Chlamydia trachomatis

  • Rickettsial infections (Rocky Mountain spotted fever, typhus fever, Q fever, tick fever)

  • Anthrax — treatment and prevention following exposure (Bacillus anthracis)

  • Acute intestinal amebiasis (alongside other medications)

  • Yaws (Treponema pallidum pertenue)

  • Severe acne (as part of a comprehensive treatment plan including other medications)

  • Other infections when penicillin is contraindicated

And for the prevention of malaria.

Doxycycline is available in generic and branded forms. Brand names include Acticlate, Doryx, Morgidox, Oracea, Targadox, and Vibramycin. It’s available as a tablet and capsule (in both immediate- and delayed-release forms), an oral suspension, a syrup, and a solution for injection.³

How do you take doxycycline?

How you take doxycycline will depend on several factors, including the infection being treated and its location in your body, your overall health, the form you take, other medications you are on, and any other medical conditions you have that may affect your body’s handling of the drug.

Drug forms and strengths

Doxycycline is available in the following forms and strengths:⁴

Doxycycline tablets (immediate-release)

  • 20mg

  • 50mg

  • 75mg

  • 100mg

  • 150mg

Doxycycline tablets (delayed-release)

  • 50mg

  • 60mg

  • 75mg

  • 100mg

  • 120mg

  • 150mg

  • 200mg

Doxycycline capsules (immediate-release)

  • 50mg

  • 75mg

  • 100mg

  • 150mg

Doxycycline capsules (delayed-release)

  • 40mg

Doxycycline syrup

  • 50mg/5mL

Doxycycline oral suspension

  • 25mg/5mL

Doxycycline powder (reconstituted for injection)

  • 100mg

Note that some strengths and forms may only be available under certain brand names.

Dose strengths and schedules vary widely with doxycycline as it treats a range of conditions. Regardless of the condition, doxycycline tablets, capsules, syrup, and oral suspension are taken orally. The oral forms may be taken with food to reduce stomach upset. Drinking plenty of fluids will help reduce the risk of esophageal irritation.⁵

The injectable solution is administered by a qualified healthcare professional in a monitored setting.

Seeing results

Doxycycline works quickly, reaching peak levels in the blood within 90 minutes to four hours. The treatment will then begin to impede bacterial replication, and the symptoms will start to improve. However, the infection typically takes at least a few days to clear.⁶

Who should not take doxycycline?

Doxycycline is contraindicated for people with known hypersensitivity to the drug or any tetracyclines.

Additionally, doxycycline should be prescribed cautiously during the last half of pregnancy and for children younger than eight years due to the risk of permanent discoloration of the teeth. However, doctors will prescribe this medication for anthrax and in cases where other drugs are contraindicated or unlikely to be effective, as its benefits for treating the infection outweigh the potential risks.⁷ ⁸

Warnings and potential side effects of doxycycline

Doxycycline (and other antibacterial agents) may trigger Clostridium difficile-associated diarrhea (CDAD), which can be severe or even fatal. If your doctor suspects you may have CDAD, they will likely discontinue doxycycline therapy.

This drug and others in its class may increase the skin’s sensitivity to sunlight. Make sure to wear sunscreen and take precautions while in the sun. Consult your doctor if you develop sunburn-like redness while taking doxycycline, as it may be necessary to discontinue treatment.

Additionally, some people taking doxycycline will experience other unwanted adverse effects.⁹

Common side effects

Common side effects, which are typically mild and resolve without intervention, include the following:

  • Poor appetite

  • Nausea and vomiting

  • Upper abdominal pain

  • Diarrhea

  • Rectal itching

  • Vaginal discharge, swelling, redness, burning, or irritation

  • Difficulty urinating

  • Dry mouth

  • Swelling of the tongue

  • Sore throat or nose

  • Back pain

  • Anxiety

  • Changes in skin, scar, nail, eye, or mouth color

Severe side effects

Severe side effects require urgent medical care. If you experience any of the following severe side effects, reach out to your doctor or seek urgent medical assistance.

  • Skin redness, peeling, blistering, rash, or hives

  • Headache

  • Visual changes, including blurred vision, double vision, or vision loss

  • Difficulty breathing or swallowing

  • Swelling of the eyes, face, lips, tongue, or throat

  • Watery or bloody stools

  • Stomach cramps

  • Unusual bleeding or bruising

  • Joint pain

  • Bone growth abnormalities

  • Tooth discoloration

  • Esophagitis or esophageal ulcer

  • Abnormal kidney function tests

  • Worsening symptoms in patients with systemic lupus erythematosus

It’s impossible to predict how your body will react to doxycycline, and you may experience side effects that aren’t listed above. If you notice any unusual symptoms while taking doxycycline, speak with your doctor.

Long-term use of doxycycline

Your doctor will decide how long you need to take doxycycline and may monitor specific blood tests if the treatment is prolonged to ensure there are no adverse effects on the functioning of your organs. However, if you’re taking it to prevent malaria, you shouldn’t take doxycycline for more than four months due to the risk of increased side effects.¹⁰

Doxycycline in pregnancy and breastfeeding

The US FDA designated doxycycline as a category D drug in pregnancy. Research involving pregnant women has demonstrated a risk, but the benefits of taking the drug may outweigh the potential risks. In a study of over 50,000 mothers (some with infants born with congenital disorders and some with children born without), researchers found a weak (but significant) association between congenital anomalies and doxycycline use during pregnancy.¹¹

However, existing research is limited and, in some cases, conflicting. There are certain situations where a doctor may decide that the therapeutic benefit of doxycycline outweighs any potential risks. For example, doxycycline is considered the most effective treatment for Rocky Mountain spotted fever in all patients, including those who are pregnant.¹²

While the current research doesn’t prove risk, and there are no adequate studies on the short- or long-term use of doxycycline in pregnancy, you should discuss current or planned pregnancies with your doctor.

Taking doxycycline during the last half of pregnancy may lead to permanent discoloration of the child’s teeth. 

Tetracyclines, including doxycycline, are excreted in human breast milk. It’s not known how much doxycycline may be passed to a nursing infant or if exposure would have lasting effects. Your doctor will consider the benefits and potential risks when deciding if you should discontinue doxycycline while breastfeeding.

Missed doses

If you miss a dose of doxycycline, take it as soon as you remember. However, if it’s nearly time for your next dose, skip the missed one and resume your usual dosing schedule.

Do not double your dose to make up for a missed one.


If you suspect you may have overdosed on doxycycline, call for emergency assistance or contact the Poison Control Helpline for information.

If someone in your care has overdosed and is experiencing severe overdose symptoms, including seizures, collapse, or unconsciousness, call 911.

Allergy information

Some people are allergic to doxycycline. If you experience signs of a drug allergy, including tongue or throat swelling, difficulty breathing, or a rash, hives, or itching, seek immediate medical care.

Interactions with other drugs

Doxycycline interacts with other medications. In particular, you should be aware of the following known interactions:¹³ ¹⁴

  • Penicillin, atovaquone: Doxycycline may make penicillin or atovaquone (Mepron) less effective.

  • Bremelanotide (Vyleesi): Taking bremelanotide may reduce doxycycline levels, making it less effective.

  • Oral contraceptives: Doxycycline may reduce the effectiveness of oral contraceptives.

  • Lithium: Doxycycline may increase the amount of lithium in the blood, increasing the risk of toxicity.

  • Isotretinoin: Isotretinoin (Accutane) and other retinoic acid derivatives, such as tretinoin (Retin-A) and acitretin (Soriatane), are contraindicated because they may increase the risk of toxicity and intracranial hypertension when taken with doxycycline.

  • Sulfonylureas: People taking doxycycline alongside sulfonylureas for type 2 diabetes may face a higher risk of developing hypoglycemia (low blood sugar).

  • Barbiturates, carbamazepine, and phenytoin: These drugs speed up your body’s processing and elimination of doxycycline, making it less available to fight an infection.

  • Drugs, multivitamins, and supplements containing iron: These preparations impair your body’s absorption of doxycycline.

  • Antacids, sucralfate (Carafate), and bismuth subsalicylate (Pepto-Bismol): Like preparations containing iron, these drugs influence the effectiveness of doxycycline by impairing your body’s absorption of the drug.

  • Ascorbic acid: Taking ascorbic acid (vitamin C) may reduce the action of doxycycline in fighting infection.

  • Digoxin: The levels of digoxin (Lanoxin) may be increased by taking doxycycline, increasing its associated risks.

  • Aminolevulinic acid: When applied topically, aminolevulinic acid (Ameluz, Levulan Kerastick) may increase the risk of sun phototoxicity and should be avoided when taking doxycycline.

  • Warfarin: Taking warfarin (Coumadin) along with doxycycline may significantly increase the risk of bleeding.

  • Migraine medicines: Dihydroergotamine (DHE, Migranal) and ergotamine (Cafergot, Ergomar) can have increased toxicity when taken with doxycycline.

This is not an exhaustive list of all possible drug interactions with doxycycline. It’s best to review your list of medications and supplements with your prescriber thoroughly to ensure there are no specific instructions for taking them with doxycycline or significant interactions.

Can I drink alcohol while taking doxycycline?

There are no known interactions between alcohol and doxycycline. However, the drug may be less effective in people with alcohol use disorder.¹⁵

What to discuss with your doctor before starting doxycycline

Doxycycline is available by prescription only, so you’ll need to meet with your doctor before you start taking it. At your appointment, it’s essential you discuss the following topics with your doctor:¹⁶

  • Any allergies you have (medical or other)

  • All vitamins, supplements, and herbs you take (even if you only take them occasionally)

  • All medications you’re presently taking, take intermittently, or plan to take

  • Any planned surgeries, including dental procedures

  • Any upcoming lab tests, as doxycycline may interfere with the results of certain tests¹⁷

  • Current or planned pregnancy or breastfeeding

  • All health conditions you currently have or have had in the past, including systemic lupus erythematosus, asthma, intracranial hypertension, yeast infections, and gastrointestinal, kidney, or liver infections or disease

  • Your use of contraceptives, as doxycycline may reduce the effectiveness of hormonal contraceptives

Stopping doxycycline

Speak with your doctor before stopping doxycycline, even if your symptoms are improving. To ensure sufficient treatment, take the full course of doxycycline prescribed for you. If you’re taking the medication for malaria prevention, your prescriber will tell you when to start and stop taking it.

Drug approval history

1967: Doxycycline was approved by the US FDA¹⁸

1994: The US FDA approved the addition of malaria prevention to the drug’s list of indicated uses¹⁹

Tips and advice for taking doxycycline

  • Drink plenty of water to reduce the risk of esophageal irritation.

  • Ask your doctor or pharmacist if you can take doxycycline with food. While taking it with food can reduce stomach upset, it may also make your medication less effective.²⁰

  • Limit sun exposure and wear sunscreen, sunglasses, and protective clothing when you go outside. Let your doctor know if you get a sunburn while taking doxycycline.²¹

  • When using doxycycline for malaria prevention, continue to use protective measures, including insect repellants and mosquito screens or nets. Doxycycline doesn’t provide complete protection from malaria.²²

Frequently asked questions

Why do I feel weird after taking doxycycline?

People taking doxycycline (and other antibiotics) may experience unusual side effects affecting the mind and body. Some adverse effects, such as anxiety and dry mouth, resolve reasonably quickly without treatment. However, if you experience any severe or lasting side effects, you should speak with your doctor.

How is doxycycline eliminated from the body?

Most doxycycline (35–60%) is excreted through urine, while the remainder is eliminated through feces.²³

Can doxycycline make you extremely tired?

Extreme tiredness is not commonly reported in patients taking doxycycline. It is more likely that you would feel tired from the infection being treated. However, it’s impossible to predict how a new drug will affect you. Speak with your doctor if you feel unusually drowsy or fatigued while taking doxycycline or any other medication.

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Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

Curious about clinical trials?

Access the latest treatments and medications. unavailable elsewhere - entirely free of charge. We make it easy to take part.