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Fosfomycin Side Effects

In Summary

More frequently reported side effects include: diarrhea, nausea, and vaginitis. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to fosfomycin: oral powder for solution

Along with its needed effects, fosfomycin may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking fosfomycin:

  • Blood in the urine
  • burning while urinating
  • cough or hoarseness
  • difficult or painful urination
  • fever or chills
  • lower back or side pain
  • painful or difficult urination
Incidence not known
  • Abdominal or stomach pain or tenderness
  • black, tarry stools
  • bloating
  • chest pain
  • clay-colored stools
  • constipation
  • dark urine
  • diarrhea
  • difficulty with swallowing
  • dizziness
  • fast heartbeat
  • headache
  • hives
  • itching
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • light-colored stools
  • loss of appetite
  • nausea or vomiting
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • rash
  • severe abdominal or stomach cramps and pain
  • shortness of breath
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen or painful glands
  • tightness in the chest
  • unpleasant breath odor
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • vomiting of blood
  • watery and severe diarrhea, which may also be bloody
  • wheezing
  • worsening of asthma
  • yellow eyes or skin

Some side effects of fosfomycin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common
  • Itching of the vagina or genital area
  • pain during sexual intercourse
  • thick, white vaginal discharge with no odor or with a mild odor
Less common
  • Acid or sour stomach
  • back pain
  • belching
  • body aches or pain
  • congestion
  • dryness or soreness of the throat
  • heartburn
  • heavy bleeding
  • indigestion
  • lack or loss of strength
  • pain
  • painful menstruation
  • runny or stuffy nose
  • skin rash
  • sneezing
  • sore throat
  • stomach discomfort or upset
  • tender, swollen glands in the neck
  • trouble with swallowing
  • voice changes
  • weakness
  • Abnormal stools
  • absent missed or irregular menstrual periods
  • blindness
  • blue-yellow color blindness
  • blurred vision
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • decreased vision
  • difficulty with moving
  • dry mouth
  • excess air or gas in the stomach or intestines
  • eye pain
  • full feeling
  • headache, severe and throbbing
  • joint pain
  • loss of appetite
  • muscle aching or cramping
  • muscle pains or stiffness
  • nervousness
  • passing gas
  • sleepiness or unusual drowsiness
  • sleeplessness
  • stopping of menstrual bleeding
  • swollen joints
  • swollen, painful, or tender lymph glands in the neck, armpit, or groin
  • trouble sleeping
  • unable to sleep
  • weight loss
Incidence not known

For Healthcare Professionals

Applies to fosfomycin: oral powder for reconstitution


Very common (10% or more): Diarrhea (up to 10.4%)
Common (1% to 10%): Nausea, abdominal pain, dyspepsia, retching, stomach ache
Uncommon (0.1% to 1%): Abnormal stools, constipation, dry mouth, flatulence, vomiting
Frequency not reported: Pseudomembranous colitis
Postmarketing reports: Toxic megacolon[Ref]

Nervous system

Very common (10% or more): Headache (up to 10.3%)
Common (1% to 10%): Dizziness
Uncommon (0.1% to 1%): Dysgeusia, paresthesia, migraine, somnolence, vertigo
Postmarketing reports: Hearing loss[Ref]


Common (1% to 10%): Vaginitis, dysmenorrhea
Uncommon (0.1% to 1%): Hematuria, dysuria, menstrual disorder[Ref]


Common (1% to 10%): Pain, asthenia, injection site phlebitis
Uncommon (0.1% to 1%): Fatigue, infection, ear disorder, fever, influenza syndrome
Frequency not reported: Facial edema[Ref]


Very rare (less than 0.01%): Anaphylactic shock
Postmarketing reports: Anaphylaxis[Ref]


Common (1% to 10%): Rhinitis, pharyngitis
Uncommon (0.1% to 1%): Dyspnea
Frequency not reported: Asthmatic attack
Postmarketing reports: Exacerbation of asthma[Ref]


Angioedema has also been reported during postmarketing experience.[Ref]

Common (1% to 10%): Rash
Uncommon (0.1% to 1%): Pruritus, skin disorder
Frequency not reported: Angioedema, urticaria[Ref]


Common (1% to 10%): Back pain
Uncommon (0.1% to 1%): Myalgia[Ref]


Increased alkaline phosphatase was generally transient and not clinically significant.[Ref]

Uncommon (0.1% to 1%): Anorexia, decreased appetite, hypernatremia and/or hypokalemia, increased alkaline phosphatase[Ref]


Increased eosinophil count, increased or decreased white blood cell count, increased and decreased platelet count, decreased hematocrit, and decreased hemoglobin were generally transient and not clinically significant.

Aplastic anemia has also been reported during postmarketing experience.[Ref]

Uncommon (0.1% to 1%): Lymphadenopathy
Rare (0.01% to 0.1%): Aplastic anemia, eosinophilia
Frequency not reported: Agranulocytosis, granulocytopenia, leukopenia, pancytopenia, thrombocytopenia, increased eosinophil count, increased or decreased white blood cell count, increased and decreased platelet count, decreased hematocrit, decreased hemoglobin[Ref]


Uncommon (0.1% to 1%): Increased ALT, increased AST
Very rare (less than 0.01%): Fatty liver
Frequency not reported: Increased bilirubin, hepatitis, cholestatic hepatitis, icterus
Postmarketing reports: Cholestatic jaundice, hepatic necrosis[Ref]

Fatty liver was completely reversible after IV fosfomycin was discontinued.

Increased bilirubin, increased ALT, and increased AST were generally transient and not clinically significant.[Ref]


Uncommon (0.1% to 1%): Tachycardia[Ref]


Uncommon (0.1% to 1%): Insomnia, nervousness
Frequency not reported: Confusion[Ref]


Very rare (less than 0.01%): Visual impairment
Frequency not reported: Unilateral optic neuritis[Ref]


1. de Jong Z, Pontonnier F, Plante P "Single-dose fosfomycin trometamol (Monuril) versus multiple-dose norfloxacin: results of a multicenter study in females with uncomplicated lower urinary tract infections." Urol Int 46 (1991): 344-8

2. Naber KG, Thyroff-Friesinger U "Fosfomycin trometamol versus ofloxacin/co-trimoxazole as single dose therapy of acute uncomplicated urinary tract infection in females: a multicentre study." Infection 18(suppl 2 (1990): s70-6

3. Jardin A "A general practitioner multicenter study: fosfomycin trometamol single dose versus pipemidic acid multiple dose." Infection 18(suppl 2 (1990): s89-93

4. "Product Information. Monurol (fosfomycin)." Forest Pharmaceuticals, St. Louis, MO.

5. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

6. Rosales MJ, Vega F "Anaphylactic shock due to fosfomycin." Allergy 53 (1998): 905-7

Some side effects of fosfomycin may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.