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Tetracycline Hydrochloride


Pronunciation: teh-truh-SIGH-kleen HIGH-droe-KLOR-ide
Class: Anti-infective agent

Trade Names

Sumycin 250
- Tablets 250 mg

Sumycin 500
- Tablets 500 mg

Sumycin Syrup
- Oral Suspension 125 mg per 5 mL

Apo-Tetra (Canada)
Nu-Tetra (Canada)


Inhibits bacterial protein synthesis.

Slideshow: View Frightful (But Dead Serious) Drug Side Effects



Tetracycline is adequately, but incompletely, absorbed from the GI tract.


Tetracycline is about 65% bound to plasma proteins (short-acting). The protein binding for intermediate and long-acting analogs is usually greater. Penetration into most body fluids and tissues is excellent. Tetracycline is distributed in varying degrees in liver, bile, lung, kidney, prostate, urine, CSF, synovial fluid, mucosa of the maxillary sinus, brain, sputum, and bone. Tetracycline crosses the placenta and enters fetal circulation and amniotic fluid.


Tetracycline is concentrated by the liver in the bile.


Tetracycline is excreted in both urine and feces at high concentrations in a biologically active form.

Special Populations

Renal Function Impairment

Because renal Cl is by glomerular filtration, excretion is significantly affected by the state of renal function.

Indications and Usage

Treatment of infections caused by susceptible strains of gram-positive and gram-negative bacteria; treatment of Rickettsia , Mycoplasma pneumoniae ; chlamydial infections including treatment of trachoma; adjunctive treatment in severe acne; treatment of susceptible infections when penicillins are contraindicated; adjunctive treatment of acute intestinal amebiasis; treatment of nongonococcal urethritis caused by Ureaplasma urealyticum ; treatment of relapsing fever due to Borrelia recurrentis .


Hypersensitivity to tetracyclines or any component.

Dosage and Administration


PO Usual dose: 1 to 2 g/day in 2 or 4 equal doses.

Mild to Moderate Infections

500 mg twice daily or 250 mg 4 times daily.

Severe Infections

500 mg 4 times daily.

Children older than 8 yr of age

PO 25 to 50 mg/kg/day in 4 equally divided doses.


PO 500 mg 4 times daily for 3 wk, accompanied by 1 g streptomycin IM twice daily the first week and daily the second week.

Severe Acne

PO Start with 1 g/day in divided doses; for maintenance, 125 to 500 mg/day (alternate-day or intermittent therapy may be adequate in some patients).

Streptococcal Infections

Treat streptococcal infections for at least 10 days.


PO Sumycin only: Total dose of 30 to 40 g in equally divided doses over 10 to 15 days. All except Sumycin : Early (less than 1 yr duration) - 500 mg 4 times daily for 15 days. More than 1 yr duration - 500 mg 4 times daily for 30 days. CDC-recommended treatment for penicillin-allergic patients: Early (less than 1 yr duration) - 500 mg 4 times daily for 14 days. More than 1 yr duration - 500 mg 4 times daily for 28 days.

Uncomplicated Gonorrhea

PO 500 mg every 6 h for 7 days.

Uncomplicated Urethral, Endocervical, or Rectal Infections Caused by Chlamydia trachomatis

PO 500 mg 4 times daily for at least 7 days.


Store capsules, tablets, and oral suspension at controlled room temperature (59° to 86°F). Protect from light and excessive heat.

Drug Interactions

Antacids (containing aluminum, calcium, and magnesium), dairy products, food, iron salts

May decrease oral absorption of tetracycline.


The action of oral anticoagulants may be increased.


Increased potential for nephrotoxicity exists; do not use together.

Oral contraceptives

May reduce effect of oral contraceptives.


May interfere with bactericidal action of penicillins.

Laboratory Test Interactions

None well documented.

Adverse Reactions


Pericarditis (as component of hypersensitivity reaction).


Dizziness; headache.


Rash; photosensitivity.


Diarrhea; nausea; vomiting; abdominal pain or discomfort; bulky, loose stools; sore throat; glossitis; anorexia; stomatitis; black hairy tongue; dysphagia; hoarseness; enterocolitis; inflammatory lesions; epigastric distress.


Increased BUN.


Hemolytic anemia; thrombocytopenia; neutropenia; anemia; thrombocytopenic purpura; eosinophilia.


Hypersensitivity, including anaphylaxis.



Category D . Avoid during pregnancy.


Excreted in breast milk.


Avoid in children younger than 8 yr of age because abnormal bone formation and discoloration of teeth may occur.

Renal Function

Excessive accumulation may occur in patients with renal function impairment, resulting in possible liver toxicity; dosage reduction may be required.


Prolonged use may result in bacterial or fungal overgrowth.

Ophthalmic use

May retard corneal epithelial healing.

Outdated product

Do not use because degradation products are highly nephrotoxic.

Pseudomembranous colitis

Consider in patients in whom diarrhea develops.

Pseudotumor cerebri (benign intracranial hypertension)

Reported in adults. Usual manifestations are headache and blurred vision.

Sensitivity reactions

Because sensitivity reactions are more likely to occur in persons with a history of allergy, hay fever, or urticaria, the preparation should be used with caution in such individuals. Cross-sensitization among the various tetracyclines is extremely common.



Nausea, vomiting, headache, increased intracranial pressure, skin pigmentation.

Patient Information

  • Review dosing schedule and prescribed length of therapy with patient. Advise patient that dose, dosing frequency, and duration of therapy are dependent on site and cause of infection.
  • Instruct patient using capsules or tablets to take prescribed dose with a full glass of water to reduce risk of esophageal irritation or ulceration.
  • Instruct patient or caregiver using oral suspension to measure and administer prescribed dose using dosing spoon, dosing syringe, or medicine cup.
  • Advise patient to take prescribed dose at least 2 h before or after meals.
  • Advise patient to take 2 h before or after antacids containing aluminum, calcium, or magnesium, preparations containing iron or zinc, milk, or other dairy products.
  • Instruct patient to complete entire course of therapy, even if symptoms of infection disappear.
  • Advise patient to discontinue therapy and contact health care provider immediately if skin rash, hives, itching, shortness of breath, or headache and blurred vision occur.
  • Advise patient that medication may cause photosensitivity (sensitivity to sunlight) and to avoid unnecessary exposure to sunlight or tanning lamps, use sunscreens, and wear protective clothing to avoid photosensitivity reactions.
  • Caution women taking oral contraceptives that tetracycline may make birth control pills less effective and to use nonhormonal forms of contraception during treatment.
  • Caution patient that drug may cause dizziness, lightheadedness, or feeling of a whirling motion and to use caution while driving or performing other hazardous tasks until tolerance is determined.
  • Advise patient to report following signs of superinfection to health care provider: black furry tongue, white patches in mouth, foul-smelling stools, vaginal itching or discharge.
  • Warn patient that diarrhea containing blood or pus may be a sign of a serious disorder and to seek medical care if noted and not treat at home.
  • Advise patient to discard any unused tetracycline by the expiration date noted on the label.

Copyright © 2009 Wolters Kluwer Health.