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Doxycycline vs. Levaquin (levofloxacin)

Doxycycline vs. Levaquin: What’s the difference?

  • Doxycycline and Levaquin (levofloxacin) are antibiotics used to treat many different types of bacterial infections.
  • Brand names for doxycycline include Vibramycin, Oracea, Adoxa, Atridox, Acticlate, Acticlate Cap, Doryx, Doxteric, Doxy, and Monodox.
  • Doxycycline and Levaquin are different types of antibiotics. Doxycycline is a tetracycline antibiotic and Levaquin is a fluoroquinolone antibiotic.
  • Side effects of doxycycline and Levaquin that are similar include diarrhea or loose stools, nausea, vomiting, and abdominal pain.
  • Side effects of doxycycline that are different from Levaquin include tooth discoloration if used in persons below 8 years of age, and exaggerated sunburn.
  • Side effects of Levaquin that are different from doxycycline include headache, constipation, difficulty sleeping, dizziness, rash, abdominal gas, and itching. Levaquin and other fluoroquinolone antibiotics have been associated with tendinitis and even rupture of tendons, particularly the Achilles tendon.

What are doxycycline and Levaquin?

Doxycycline is a tetracycline class antibiotic used to treat a variety of infections, such as respiratory tract infections due to Streptococcus pneumoniae, Hemophilus influenzae, or Mycoplasma pneumoniae. It is also used to treat nongonococcal urethritis (due to Ureaplasma), Rocky Mountain spotted fever, cholera, chancroid, typhus, brucellosis, anthrax, syphilis, acne, and periodontal disease.

Levaquin (levofloxacin) is a fluoroquinolone antibiotic used to treat infections of the sinuses, skin, lungs, ears, airways, bones, and joints caused by susceptible bacteria; to treat urinary infections and prostatitis (infection of the prostate); infectious diarrhea caused by E. coli, Campylobacter jejuni, and Shigella bacteria; obstetric infections, including mastitis (infection of the breast); inhalational anthrax exposure; and plague caused by Yersinia pestis.


Bowel regularity means a bowel movement every day.
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What are the side effects of doxycycline and Levaquin?


Doxycycline is generally well-tolerated. The most common side effects are:

Tetracyclines, such as doxycycline, may cause tooth discoloration if used in persons below 8 years of age. Exaggerated sunburn can occur with tetracyclines; therefore, minimize sunlight exposure during treatment.


Serious side effects and warnings include:

  • Levaquin as well as other antibiotics in the fluoroquinolone class of antibiotics have been associated with tendinitis and even rupture of tendons, particularly the Achilles tendon.
  • Fluoroquinolones have neuromuscular blocking activity and can worsen muscle weakness in individuals with myasthenia gravis.

The most frequently reported side effects are:

Less common side effects include:

Rare allergic reactions that have been described are:

Possible serious side effects of Levaquin include:

Other serious side effects and adverse events of Levaquin include:

  • Levaquin should be used with caution in patients with central nervous system diseases such as seizures, because rare seizures have been reported in patients receiving Levaquin.
  • Levaquin should be avoided in children and adolescents less than 18 years of age, as safe use in these patients has not been established.
  • Many antibiotics, including Levaquin, can alter the normal bacteria in the colon and encourage overgrowth of a bacterium responsible for the development of inflammation of the colon, (C. difficile or pseudomembranous colitis). Patients who develop signs of pseudomembranous colitis after starting Levaquin (diarrhea, fever, abdominal pain, and possibly shock) should contact their doctor immediately.
  • Patients taking Levaquin can develop sensitivity of the skin to direct sunlight (photosensitivity) and should avoid exposure to sunlight or use sunblock.
  • Fluoroquinolones worsen low blood glucose levels when combined with sulfonylureas (for example, glyburide [Micronase, Diabeta, Glynase, Prestab]).
  • Because of serious side effects associate with fluoroquinolones, they should not be used for treating uncomplicated urinary tract infections, acute bacterial exacerbation of chronic bronchitis or acute bacterial sinusitis unless there are no other alternatives.

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What is the dosage of doxycycline vs. Levaquin?


  • The absorption of doxycycline is not markedly affected by food and, therefore, it can be taken with meals.
  • For most infections, doxycycline is taken once or twice daily for 7 to 14 days.
  • For adult infections, the usual dose of oral doxycycline is 200 mg on the first day of treatment (100 mg every 12 hours) followed by a dose of 100 to 200 mg/day as a single dose or divided and administered twice daily.


  • The usual dose is 250 to 750 mg given once daily for 3 to 14 days depending on the type of infection.
  • Anthrax is treated with 500 mg daily for 60 days.
  • It is important to take oral formulations at least 2 hours before or 2 hours after any antacid or mineral supplement containing iron, calcium, zinc, or magnesium, since these bind Levaquin and prevent its absorption into the body.

What drugs interact with doxycycline and Levaquin?


  • Do not take doxycycline at the same time as aluminum-, magnesium-, or calcium-based antacids, such as Mylanta, Maalox, Tums, or Rolaids because, like food, these medications bind doxycycline in the intestine and prevent its absorption. Similarly, do not take doxycycline with minerals (such as calcium or iron) or with bismuth subsalicylate (Pepto Bismol).
  • Doxycycline may enhance the activity of warfarin (Jantoven, Coumadin) and cause excessive "thinning" of the blood leading to exaggerated bleeding, necessitating a reduction in the dose of warfarin. Phenytoin (Dilantin), carbamazepine (Tegretol), and barbiturates (such as phenobarbital) may enhance the metabolism (destruction) of doxycycline, thus making it less effective.
  • Doxycycline may interfere with the action of penicillins and should not be combined with penicillins.
  • Doxycycline may reduce the effectiveness of oral contraceptives.
  • Combining tetracycline and methoxyflurane (Penthrane) may reduce kidney function.


  • Iron, calcium, zinc, or magnesium can attach to Levaquin and other fluoroquinolones and prevent their absorption from the intestine into the blood. Therefore, products that contain iron, calcium, zinc, or magnesium (for example, antacids) should be taken at least 2 hours before or 2 hours after Levaquin. Other drugs that contain these minerals and can similarly interact with Levaquin include sucralfate (Carafate) and didanosine (Videx, Videx EC).
  • Taking nonsteroidal anti-inflammatory drugs (NSAIDs) with Levaquin may increase the risk of central nervous system stimulation, resulting in over-excitation. There have been reports of changes in blood sugar (increases and decreases) in patients treated with fluoroquinolones and antidiabetic agents.
  • Fluoroquinolones may increase the effect of warfarin (Coumadin, Jantoven).

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Are doxycycline and Levaquin safe to use while pregnant or breastfeeding?


  • Tetracycline antibiotics, such as doxycycline, can have toxic effects on development of bone in the fetus. Therefore, tetracyclines are not recommended during pregnancy unless there is no other appropriate antibiotic.
  • Doxycycline is secreted into breast milk but the extent of absorption by the breastfed infant is not known. Since tetracyclines can cause toxic effects on bone, the use of tetracyclines in nursing mothers is of concern. The doctor must decide whether to recommend that a nursing mother discontinue nursing during treatment with tetracyclines or change to a different antibiotic.


  • Levaquin is not recommended for use in pregnant women, since Levaquin causes joint and bone deformities in juvenile animals of several species.
  • Levaquin is excreted in breast milk. Mothers should decide whether to stop breastfeeding or discontinue Levaquin.

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