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Doxycycline is currently the 113th most commonly prescribed drug in the United States. In 2017 alone, there were over 6,600,000 prescriptions. Considering how popular this drug is right now, it pays to know a little bit more about this medication, including how long doxycycline stays in your system.

The Journal of Microbial Chemotherapy states the following information regarding doxycycline half-life:

Mean effective half-life: is about 12 to 25 h

Doxycycline has an oral bioavailability of over 80%.

FAQ

How long does doxycycline stay in your system?

In people with a creatinine clearance of about 75 mL/min, excretion by the kidney is about 40% in 72 hours. In people with a creatinine clearance below 10 mL/min, excretion can be as low as 1-5% in 72 hours.

The half-life of this drug is about 12 to 25 hours long and it takes roughly 5 half-lives to clear a substance from the body. That means it could take approximately 60 hours (2.5 days) to 125 hours (over 5 days) for the body to clear this antibiotic.

Doxycyline is likely detectable in your system for the following time frames:

  • Blood/Serum: Peak serum concentrations in adults is roughly 2.6 mcg/mL, achieved after about 2 hours following a single 200 mg oral dose; after 24 hours, that dropped to 1.45 mcg/mL
  • Breastmilk: The American Academy of Pediatrics recommends not providing breastfeeding within 24 hours of taking Flagyl, another antibiotic; while doxycyline can pass to breastmilk, it is not known what the long-term effects of this drug are on a breastfeeding infant

(Numbers above are merely estimates, and may vary based on several factors, such as age and other medical conditions.)

How long does it take doxycycline to get out of your system?

Doxycycline is excreted in the urine and feces at high concentrations and in a biologically active form. In people with a creatinine clearance of about 75 mL/min, excretion by the kidney is about 40% in 72 hours. In people with a creatinine clearance below 10 mL/min excretion can be as low as 1-5% in 72 hours.

How long does it take for doxycycline to work for bacterial infection?

For most infections, symptoms start easing within a few days. However, it is essential that you finish the whole cycle as prescribed by your doctor.

Why should you not lie down after taking doxycycline?

If you lie down soon after you have taken doxycycline, the reflux of the drug can cause irritation to your throat.

Can I take doxycycline less than 12 hours apart?

No. Always follow your doctor’s indications.

What bacteria does doxycycline kill?

  • Mycoplasma pneumoniae
  • Chlamydia trachomatis
  • Chlamydophila psittaci
  • Chlamydia trachomatis
  • Chlamydia trachomatis
  • Chlamydia trachomatis
  • Ureaplasma urealyticum
  • Borrelia recurrentis
  • Haemophilus ducreyi
  • Yersinia pestis
  • Francisella tularensis
  • Vibrio cholerae
  • Campylobacter fetus
  • Bartonella bacilliformis
  • Klebsiella granulomatis
  • Escherichia coli
  • Enterobacter aerogenes
  • Shigella species
  • Acinetobacter species
  • Haemophilus influenzae
  • Klebsiellaspecies
  • Streptococcus pneumoniae
  • Bacillus anthracis

When penicillin is contraindicated (advised against), doxycycline is an alternative drug in the treatment of the following bacteria:

  • Neisseria gonorrhoeae
  • Treponema pallidum
  • Treponema pallidum subspecies pertenue
  • Listeria monocytogenes
  • Fusobacterium fusiforme
  • Actinomyces israelii
  • Clostridium species

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.


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