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Fosfomycin Side Effects

Medically reviewed by Last updated on Aug 7, 2022.

Applies to fosfomycin: oral powder for solution.

Serious side effects of Fosfomycin

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

Other side effects of Fosfomycin

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 granule for reconstitution, 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, antibiotic-associated colitis, oral paresthesias (temporary tingling of mouth, tongue, cheek)[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, temporary alterations of taste (dysgeusia, hypogeusia)[Ref]


Common (1% to 10%): Vaginitis, dysmenorrhea, vulvovaginitis

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, anaphylactic reactions (including anaphylactic shock), hypersensitivity[Ref]


Common (1% to 10%): Rhinitis, pharyngitis

Uncommon (0.1% to 1%): Dyspnea

Frequency not reported: Asthmatic attack

Postmarketing reports: Asthma, 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, urticaria

Frequency not reported: Angioedema[Ref]


Common (1% to 10%): Back pain

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


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

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

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]


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%): 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]


Uncommon (0.1% to 1%): Tachycardia

Postmarketing reports: Hypotension[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]

Frequently asked questions


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

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. 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

4. "Product Information. Monurol (fosfomycin)." Forest Pharmaceuticals (2001):

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

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.