Tetracycline antibiotic (oral)
Tetracycline is an oral antibiotic used for several bacterial infections (respiratory, urinary, acne and others). It belongs to the tetracycline class, which must not be used in pregnancy nor in children up to 8 years of age because it permanently stains teeth. It should be taken on an empty stomach, away from milk, antacids, iron and zinc, which reduce its absorption.
Also known as: Tetraciclina
Tetracycline + Warfarin: tetracyclines may depress plasma prothrombin activity; a downward adjustment of the anticoagulant dosage may be required.
Tetracyclines have been shown to depress plasma prothrombin activity, potentiating the effect of oral anticoagulants such as warfarin. In patients on anticoagulant therapy starting a tetracycline, a downward adjustment of the anticoagulant dose may be required. The INR should be closely monitored at the start and end of the antibiotic, and the patient alerted to signs of bleeding — gum bleeding, bruising or dark stools. The interaction is especially relevant in the elderly and in patients with unstable INR.
Tetracycline + warfarin: tetracyclines depress prothrombin — adjust the anticoagulant dose and monitor INR.
Tetracyclines have been shown to depress plasma prothrombin activity, potentiating the effect of oral anticoagulants.
Monitor INR and signs of bleeding.
Bleeding, bruising or INR above target.
Monitor INR during the combination and adjust the warfarin dose as needed.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94 ; approved Warfarin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=541c9a70-adaf-4ef3-94ba-ad4e70dfa057
Tetracycline + Ampicillin: bacteriostatic drugs may interfere with the bactericidal action of penicillins; the combination should be avoided.
Bacteriostatic drugs, such as tetracycline, may interfere with the bactericidal action of penicillins (ampicillin), reducing the effectiveness of treatment for serious infections. The tetracycline label advises avoiding the combination with penicillins. In practice, the combination is sometimes used intentionally in mixed infections; in those cases, consider the potential antagonism and, whenever possible, choose an alternative or separate the regimen. Monitor the clinical response of the infection.
Tetracycline + ampicillin: avoid — the bacteriostatic effect of tetracycline may interfere with the bactericidal action of penicillin.
Tetracycline, being bacteriostatic, may interfere with the bactericidal action of ampicillin when used together.
Monitor therapeutic efficacy of the infection.
Therapeutic failure of the treated infection.
Avoid the combination; if needed, separate dosing and consider an alternative.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94 ; approved Ampicillin label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3b683547-48ac-48ca-8fd4-6866fd17be34
Tetracycline + Antacids (with aluminum, calcium or magnesium): tetracycline absorption is impaired by chelation. Separate dosing times.
Antacids containing aluminum, calcium or magnesium chelate tetracycline in the gastrointestinal lumen, forming insoluble complexes that reduce absorption and the effectiveness of the antibiotic. The tetracycline label documents this interaction. The practical solution is to separate tetracycline dosing from antacids by at least 2–4 hours, preferring tetracycline on an empty stomach. In urinary or systemic infections, reduced absorption may compromise bacterial eradication; monitor the clinical response.
Tetracycline + antacids: absorption is impaired by chelation — separate dosing by 2–4 hours.
Antacids with aluminum, calcium or magnesium chelate tetracycline in the gastrointestinal lumen, reducing its absorption and efficacy.
Monitor antibiotic efficacy.
Therapeutic failure of the infection.
Separate tetracycline dosing from antacids by at least 2–4 hours.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94 ; approved Antacids label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0a13ac81-0c63-48c1-bbb0-f6e67f97b896
Tetracycline + Zinc: tetracycline absorption is impaired by chelation with preparations containing zinc. Separate dosing times.
Preparations containing zinc chelate tetracycline in the gut, reducing its absorption and antibiotic efficacy — an interaction documented in the tetracycline label. Separating dosing by at least 2–4 hours minimizes the problem. Relevant in patients taking zinc supplements (common in dermatology and supplementation) or multivitamin formulations. Monitor the response to antibiotic therapy.
Tetracycline + zinc: absorption is impaired by chelation — separate dosing by 2–4 hours.
Preparations containing zinc chelate tetracycline in the gut, reducing its absorption and efficacy.
Monitor antibiotic efficacy.
Therapeutic failure of the infection.
Separate tetracycline dosing from zinc supplements by at least 2–4 hours.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94 ; approved Zinc label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=49698d00-f44b-4b1f-ae34-6b9067911757
Tetracycline + Iron: tetracycline absorption is impaired by chelation with preparations containing iron. Separate dosing times.
Preparations containing iron chelate tetracycline in the gastrointestinal lumen, reducing its absorption and efficacy — an interaction documented in the label. It is especially relevant in patients with iron-deficiency anaemia treated with ferrous sulfate. Separate tetracycline dosing from iron by at least 2–4 hours and, ideally, take tetracycline on an empty stomach. Monitor the clinical response to infection, especially in urinary tract infections.
Tetracycline + iron: absorption is impaired by chelation — separate dosing by 2–4 hours.
Preparations containing iron chelate tetracycline in the gastrointestinal lumen, reducing its absorption and efficacy.
Monitor antibiotic efficacy.
Therapeutic failure of the infection.
Separate tetracycline dosing from iron supplements by at least 2–4 hours.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94 ; approved Iron label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=73d1f079-d8eb-44f4-b33d-05fb25b80c8f
Tetracycline + Calcium: tetracycline absorption is impaired by chelation with preparations containing calcium. Separate dosing times.
Calcium-containing products (antacids, supplements, large amounts of milk) chelate tetracycline in the gastrointestinal lumen, reducing its absorption and efficacy — an interaction documented in the label. Separate dosing by at least 2–4 hours. Relevant in patients on calcium supplementation (osteoporosis) or prolonged antacid therapy. Monitor the response to antibiotic therapy.
Tetracycline + calcium: absorption is impaired by chelation — separate dosing by 2–4 hours.
Antacids and supplements with calcium chelate tetracycline in the gastrointestinal lumen, reducing its absorption and efficacy.
Monitor antibiotic efficacy.
Therapeutic failure of the infection.
Separate tetracycline dosing from calcium-containing products by at least 2–4 hours.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94 ; approved Calcium carbonate label: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=24cec2bc-cf12-b513-e063-6394a90a9447
Calcium in dairy products chelates tetracycline in the GI lumen and markedly reduces its absorption — "Food and some dairy products also interfere with absorption" (label).
Do not take with milk, yoghurt or dairy; take on an empty stomach, 1 hour before or 2 hours after meals.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label (USP): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94
Tetracyclines cause cutaneous photosensitivity reactions — exaggerated sunburn and rashes with sun or ultraviolet light exposure.
Avoid prolonged sun exposure and ultraviolet light (including tanning beds); use sunscreen and protective clothing.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label (USP): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94
Tetracycline is eliminated mainly renally; in renal impairment it may accumulate and worsen azotaemia — and the label associates liver failure in pregnant women with renal disease.
Use with caution and reduce dose or interval in renal impairment; monitor renal function.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label (USP): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94
"The use of drugs of the tetracycline-class during tooth development (last half of pregnancy, infancy and childhood to the age of 8 years) may cause permanent discoloration of the teeth" (label); "Pregnant women with renal disease may be more prone to develop tetracycline-associated liver failure".
Contraindicated in the second half of pregnancy and in children up to 8 years; avoid whenever possible during pregnancy.
DailyMed/FDA (NIH/NLM) — approved Tetracycline label (USP): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94
Permanent tooth discoloration during development (second half of pregnancy); "Pregnant women with renal disease may be more prone to develop tetracycline-associated liver failure".
Avoid in the second half of pregnancy; use only if absolutely necessary.
Tetracyclines are excreted in breast milk; risk of tooth discoloration in the infant — avoid during breastfeeding.
No specific contraception required (no documented teratogenic effect on the fetus in the first trimester, but avoid in pregnancy).
DailyMed/FDA (NIH/NLM) — approved Tetracycline label (USP): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=02e88b4a-57ae-4ef6-ba48-97c657202b94
Clinical and educational support tool. The information does not replace a medical prescription or the opinion of a qualified healthcare professional.
Broad-spectrum bacteriostatic antibiotic active against Gram-positive and Gram-negative bacteria, rickettsiae, mycoplasmas and chlamydiae; useful in penicillin-allergic patients.
Inhibits bacterial protein synthesis by reversible binding to the 30S ribosomal subunit, blocking aminoacyl-tRNA binding to the mRNA-ribosome complex (bacteriostatic effect).
Oral absorption is incomplete and greatly reduced by chelation: "impaired by antacids containing aluminum, calcium or magnesium and preparations containing iron, zinc or sodium bicarbonate"; "Food and some dairy products also interfere with absorption" — take on an empty stomach, 1 h before or 2 h after meals.
Minimally metabolised; eliminated mainly in urine by glomerular filtration (about 60% in 24 h with normal renal function).
Half-life of about 6–11 hours with normal renal function (renal elimination); prolonged in renal impairment — may accumulate.
