Generic name: Enoxacin.

Penetrex is a fluoroquinolone antibiotic/anti-infective. It is used to treat a variety of bacterial infections.

Quick Facts About Penetrex


Used to treat urinary tract infections, including cystitis (inflammation of inner lining of bladder caused by bacterial infection), and certain sexually transmitted diseases such as gonorrhea.

Penetrex Dosage

Take regularly; try not to miss doses to keep constant level in blood and urine — Penetrex will be most effective in this way. Take with a full glass of water either 1 hour before or 2 hours after a meal. Do not take more than prescribed dose. Use all of the prescription; otherwise at risk for symptoms returning.

  • Usual adult dose: for uncomplicated urinary tract infections — 200 milligrams taken every 12 hours for 7 days. Other urinary tract infections — 400 milligrams taken every 12 hours for 14 days. For sexually transmitted disease (gonorrhea) — 400 milligrams taken in a single dose.
  • Usual child dose: not generally prescribed for children.
  • Missed dose: take as soon as possible, unless almost time for next dose. In that case, do not take missed dose; go back to regular schedule. Do not double doses.

Penetrex Side Effects

Overdose symptoms:

no specific information available. If you suspect an overdose, immediately seek medical attention.

More common side effects: nausea, vomiting.

Less common or rare Penetrex side effects: abdominal pain, agitation, back pain, bloody stools, chest pain, chills, confusion, constipation, convulsions, cough, depression, diarrhea, difficult or labored breathing, dizziness, dry mouth and throat, emotional changeability, excessive sweating, fainting, fatigue, fever, fluid retention and swelling, fungal infection, gas, general feeling of illness, hallucinations, headache, hives, inability to hold urine, indigestion, inflammation of eyes, inflammation of large intestine, inflammation of mouth, inflammation of stomach, inflammation of vagina, joint pain, kidney failure, lack of coordination, loss of appetite, loss of feeling of identity, loss of memory, mental disorders, muscle pain, nosebleed, overactivity, palpitations, purple or red skin spots, rapid heartbeat, ringing in ears, sensitivity to light, skin eruptions, skin peeling, sleepiness, tingling or pins and needles, tremor, twitching, vaginal yeast infection, vision disturbances, weakness.


Inform your doctor before combining Penetrex with:

bismuth subsalicylate (Pepto-Bismol), caffeine, cyclosporine (Sandimmune), digoxin (Lanoxin), ranitidine (Zantac), sucralfate (Carafate), theophylline (Theo-Dur), warfarin (Coumadin).

Check with your doctor before using antacids containing calcium, magnesium, or aluminum, such as Maalox and Turns, or vitamins or products containing iron or zinc. 

Special Cautions

If pregnant or planning to become pregnant, inform ? your doctor immediately. May appear in breast milk; could affect a nursing infant.

No special precautions apply to seniors.

Not generally prescribed for children.

  • Has caused severe or fatal reactions, sometimes after first dose. If you develop any of the following symptoms, immediately seek medical help: confusion, convulsions, difficulty breathing, hallucinations, hives, itching, lightheadedness, loss of consciousness, rash, restlessness, swelling in face or throat, tingling, or tremors.
  • Inform your doctor if you have experienced diarrhea when taking other antibacterial medications, or develop diarrhea at the start of Penetrex therapy. May cause bowel inflammation, which could be life-threatening.
  • May cause drowsiness and impair your ability to drive a car or operate machinery. Do not take part in any activity that requires alertness.
  • Should not take if sensitive to or allergic to this or other quinolone antibiotics such as Cipro and Floxin.
  • Use with caution if you have epilepsy, severe hardening of the arteries in the brain, and other seizure-inducing conditions.
  • Avoid overexposure to sunlight. Immediately stop taking Penetrex if you experience a severe reaction such as skin rash.

Note: provides accurate and independent information prescription pills, over-the-counter medicines and natural products. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment. If you have questions about  dosage, or Penetrex side effects, please contact your healthcare provider