Doxycycline dosage
Doxycycline is one of the few antibiotics where how you swallow it matters almost as much as how much you swallow. The FDA label's usual adult regimen is 200 mg on day one (100 mg every 12 hours), then 100 mg a day — but the same label carries a warning about esophagitis and esophageal ulceration in patients who took the capsule right before bed. Every number below is quoted from the doxycycline hyclate prescribing information. PharmaRanks rates medications independently and sells nothing; this page is a reference, not a prescription.
This is reference, not a dosing instruction. Doxycyclineis prescription-only and the dose is individualized and titrated by a prescriber to your condition, response, kidney/liver function and other medicines. The figures below are the FDA label’s — do not start, change or stop a dose based on this page.
Approved for: A broad-spectrum tetracycline antibiotic labeled for rickettsial infections (Rocky Mountain spotted fever, typhus, Q fever), respiratory infections, urethral/endocervical/rectal chlamydial infections, nongonococcal urethritis, uncomplicated gonorrhea, syphilis in penicillin-allergic patients, acute epididymo-orchitis, cholera, plague, tularemia, malaria prophylaxis, and inhalational anthrax post-exposure. The label also states that "in severe acne, doxycycline may be useful adjunctive therapy." Separate low-dose products are labeled for periodontitis (20 mg) and the inflammatory lesions of rosacea (40 mg).
Available as: Doxycycline hyclate capsules 50 mg and 100 mg; doxycycline hyclate tablets 20 mg (Periostat, periodontitis only) and 100 mg; delayed-release tablets 50, 75, 100, 150 and 200 mg; doxycycline 40 mg delayed-release capsules (Oracea, rosacea only); oral suspension and syrup.
| Use | What the label says |
|---|---|
| Adults — usual dose | "The usual dose of oral doxycycline is 200 mg on the first day of treatment (administered 100 mg every 12 hours) followed by a maintenance dose of 100 mg/day." The label adds that the maintenance dose may be given as a single daily dose or as 50 mg every 12 hours, and that "in the management of more severe infections (particularly chronic infections of the urinary tract), 100 mg every 12 hours is recommended." |
| Chlamydia — urethral, endocervical or rectal infection | "100 mg, by mouth twice a day for 7 days." The same 100 mg twice daily for 7 days applies to nongonococcal urethritis caused by C. trachomatis or Ureaplasma urealyticum. |
| Uncomplicated gonorrhea (except anorectal infection 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." Note: current CDC treatment guidance for gonorrhea has moved to ceftriaxone — this is the labeled regimen, not the current first-line one. |
| Syphilis (penicillin-allergic patients) | Early syphilis: "100 mg, by mouth, twice a day for 2 weeks." Syphilis of more than one year's duration: "100 mg, by mouth, twice a day for 4 weeks." |
| Acute epididymo-orchitis (C. trachomatis or N. gonorrhoeae) | "100 mg, by mouth, twice a day for at least 10 days." |
| Streptococcal infections | "When used in streptococcal infections, therapy should be continued for 10 days." |
| Malaria prophylaxis | "For adults, the recommended dose is 100 mg daily." "For children over 8 years of age, the recommended dose is 2 mg/kg given once daily up to the adult dose." The label directs prophylaxis to begin 1 to 2 days before travel to the malarious area, continue daily during travel and for 4 weeks after the traveler leaves. |
| Inhalational anthrax (post-exposure) | Adults: "100 mg of doxycycline, by mouth, twice a day for 60 days." Children weighing less than 45 kg: "2.2 mg/kg of body weight by mouth, twice a day for 60 days." Children 45 kg or more receive the adult dose. |
| Acne / rosacea (low-dose products) | The standard doxycycline label gives no separate acne dose — it says only that "in severe acne, doxycycline may be useful adjunctive therapy," so dermatologists typically use the usual 100 mg regimens off the general label. Two sub-antimicrobial products have their own labeled doses: Periostat 20 mg tablets "twice daily at 12 hour intervals" as an adjunct to scaling and root planing for periodontitis (up to 9 months), and Oracea 40 mg delayed-release capsules — "one capsule (40 mg) should be taken once daily in the morning on an empty stomach" — for the inflammatory lesions (papules and pustules) of rosacea in adults. The Oracea label warns this formulation "should not be used for treating bacterial infections." |
| Lyme disease | Doxycycline is not given a Lyme-specific regimen in the doxycycline hyclate label's dosage section; the label covers Borrelia through its tetracycline-susceptible-organism indications. Doses used clinically follow IDSA guidance rather than a labeled number, so we do not state one here — ask the prescriber. |
| Children (weight-based) + the age limit | For children weighing 45 kg or less and older than 8 years: "4.4 mg/kg of body weight divided into two doses on the first day of treatment, followed by a maintenance dose of 2.2 mg/kg of body weight administered as a single dose or divided into two doses." For severe or life-threatening infections the label sets no age floor — it applies to any child under 45 kg: "For all pediatric patients weighing less than 45 kg with severe or life-threatening infections (e.g., anthrax, Rocky Mountain spotted fever), the recommended dosage is 2.2 mg/kg of body weight administered every 12 hours." The over-8 restriction above governs only the less-severe 4.4 → 2.2 mg/kg schedule. Children over 45 kg get the usual adult dose. The label's own restriction: use doxycycline in pediatric patients 8 years of age or less "only when the potential benefits are expected to outweigh the risks in severe or life-threatening conditions" — because tetracyclines during tooth development can permanently discolor teeth. What the label does NOT say, but CDC and the AAP do: short courses of 10 days or fewer for suspected rickettsial disease (Rocky Mountain spotted fever, ehrlichiosis, anaplasmosis) have not been shown to stain teeth, and doxycycline is the recommended treatment at any age for those infections. |
Maximum dose
The label sets no single universal maximum. The highest labeled oral figures are 100 mg every 12 hours for severe infections (200 mg/day), and 300 mg stat followed by a second 300 mg dose one hour later as the alternate single-visit regimen for uncomplicated gonorrhea. The intravenous label’s usual daily dosage is 100 to 200 mg, with a labeled exception: "In the treatment of primary and secondary syphilis, the recommended dosage is 300 mg daily for at least 10 days." The general doxycycline label carries an all-caps caution that "THE USUAL DOSAGE AND FREQUENCY OF ADMINISTRATION OF DOXYCYCLINE DIFFERS FROM THAT OF THE OTHER TETRACYCLINES. EXCEEDING THE RECOMMENDED DOSAGE MAY RESULT IN AN INCREASED INCIDENCE OF SIDE EFFECTS."
Dose adjustments
Kidneys: doxycycline is the tetracycline that usually does not need renal dose reduction. The label states that "studies to date have indicated that administration of doxycycline at the usual recommended doses does not lead to excessive accumulation of doxycycline in patients with renal impairment," and warns that other tetracyclines can cause azotemia in renal disease. Swallowing: "Administration of adequate amounts of fluid along with capsule and tablet forms of drugs in the tetracycline class is recommended to wash down the drugs and reduce the risk of esophageal irritation and ulceration" — a full glass of water, and stay upright afterward. Food and milk: contrary to the older tetracycline rule, the doxycycline label states "the absorption of doxycycline is not markedly influenced by simultaneous ingestion of food or milk," and that "if gastric irritation occurs, it is recommended that doxycycline be given with food or milk." Antacids and minerals are the real problem: "absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, and iron-containing preparations," and also by bismuth subsalicylate — separate these from your dose. Doxycycline can also reduce prothrombin activity in patients on anticoagulants and may reduce the effectiveness of oral contraceptives; barbiturates, carbamazepine, phenytoin and rifampin shorten its half-life.
Dosing safety — read before you rely on any number
Esophageal injury is the classic labeled harm: "rare instances of esophagitis and esophageal ulcerations have been reported in patients receiving capsule and tablet forms of the drugs in the tetracycline class. Most of these patients took medications immediately before going to bed." Take each dose with a full glass of water and stay upright — do not lie down right after. Photosensitivity: an exaggerated sunburn reaction can occur; avoid excessive sunlight or artificial ultraviolet light and stop the drug if phototoxicity appears. Teeth: use during tooth development ("last half of pregnancy, infancy and childhood to the age of 8 years") may cause permanent yellow-gray-brown discoloration and enamel hypoplasia; doxycycline can cause fetal harm and is generally avoided in pregnancy. Also labeled: intracranial hypertension (headache, vision changes), C. difficile-associated diarrhea, overgrowth of nonsusceptible organisms including fungi, and rare severe skin reactions. Finish the full course even once you feel better — stopping early drives resistance and relapse.
Bottom line
For most infections the labeled adult regimen is 100 mg every 12 hours on day one (200 mg total), then 100 mg daily, or 100 mg every 12 hours if the infection is severe. Children over 8 and under 45 kg get 4.4 mg/kg on day one, then 2.2 mg/kg; for children 8 and under the label still gives the 2.2 mg/kg every-12-hours dose for severe or life-threatening infections, naming Rocky Mountain spotted fever and anthrax, and CDC and AAP likewise endorse doxycycline for rickettsial disease at any age. Whatever the dose, swallow it with a full glass of water, stay upright, keep antacids and iron well away from it, and stay out of strong sun.
Frequently asked questions
What is the doxycycline dosage for adults?
The FDA label's usual adult dose is 200 mg on the first day, given as 100 mg every 12 hours, then a maintenance dose of 100 mg per day — either once daily or as 50 mg every 12 hours. For more severe infections, including chronic urinary tract infections, the label recommends staying on 100 mg every 12 hours. STI regimens are 100 mg twice daily, typically for 7 days.
How long do you take doxycycline?
It depends on what's being treated, and the label gives specific durations: 7 days for chlamydia, nongonococcal urethritis and uncomplicated gonorrhea; at least 10 days for acute epididymo-orchitis; 10 days for streptococcal infections; 2 weeks for early syphilis and 4 weeks if syphilis has lasted more than a year; 60 days for anthrax post-exposure; and for malaria, daily from 1-2 days before travel through 4 weeks after leaving the malarious area. Finish the course your prescriber set, even if you feel better on day three.
Can you take doxycycline with food or milk?
Yes — and this is where doxycycline differs from older tetracyclines. The label states that "the absorption of doxycycline is not markedly influenced by simultaneous ingestion of food or milk," and it explicitly recommends taking it with food or milk if the drug upsets your stomach. What genuinely blocks absorption is antacids containing aluminum, calcium or magnesium, iron supplements, and bismuth subsalicylate (Pepto-Bismol) — space those apart from your dose. The 40 mg rosacea capsule (Oracea) is the exception: its own label says take it on an empty stomach.
What is the doxycycline dose for acne?
The general doxycycline label gives no separate acne regimen — it says only that "in severe acne, doxycycline may be useful adjunctive therapy," so prescribers use the usual 100 mg doses. Two low-dose products do have their own labeled acne-adjacent regimens: Oracea 40 mg delayed-release capsules once daily on an empty stomach for the inflammatory papules and pustules of rosacea, and Periostat 20 mg twice daily for periodontitis. Both are sub-antimicrobial doses and are not for treating infections.
Why can't you lie down after taking doxycycline?
Because the capsule can lodge in the esophagus and burn it. The label reports "rare instances of esophagitis and esophageal ulcerations" in people taking capsule and tablet tetracyclines, and notes that "most of these patients took medications immediately before going to bed." The countermeasure is in the label too: wash the dose down with adequate fluid — a full glass of water — and stay upright long enough for it to clear. Avoid taking your last dose as you're getting into bed.
Can children take doxycycline?
Children over 8 years old can: 4.4 mg/kg divided into two doses on day one, then 2.2 mg/kg daily (or 2.2 mg/kg every 12 hours for severe infections), with children over 45 kg taking adult doses. For children 8 and under, the label says to use doxycycline "only when the potential benefits are expected to outweigh the risks in severe or life-threatening conditions," because tetracyclines during tooth development can permanently stain teeth. CDC and the American Academy of Pediatrics go further on one point: short courses of 10 days or less for suspected Rocky Mountain spotted fever and other rickettsial diseases have not been shown to cause visible staining, and doxycycline is the recommended treatment at any age for those infections.
Sources
More guides for Doxycycline
Other dosage guides: Metformin dosage · Amoxicillin dosage · Prednisone dosage · Gabapentin dosage · Ibuprofen dosage · Lisinopril dosage · Levothyroxine dosage · Omeprazole dosage · Ondansetron dosage · Albuterol dosage · Allopurinol dosage · Methotrexate dosage · Alendronate dosage · Fluconazole dosage · Acetaminophen dosage · Diphenhydramine dosage · Naproxen dosage · Aspirin dosage · Cetirizine dosage · Dimenhydrinate dosage · Famotidine dosage.
Doses are transcribed from the FDA-approved label and are general reference information, not medical advice or a personal dose. Only a prescriber can set or change your dose. If you think you took too much, contact Poison Control (1-800-222-1222) or 911.