Fosfomycin Side Effects

Not all side effects for fosfomycin may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

Applies to fosfomycin: oral powder for solution

In addition to its needed effects, some unwanted effects may be caused by fosfomycin. In the event that any of these side effects do occur, they may require medical attention.

You should check with your doctor immediately if any of these side effects occur when 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 of the side effects that can occur with fosfomycin may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

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
  • Hearing loss

For Healthcare Professionals

Applies to fosfomycin: oral powder for reconstitution


In general, fosfomycin is well tolerated with minimal and transient adverse reactions. Adverse effects, if they occur, are usually short-lived due to the fact that fosfomycin is given as a single dose.


Gastrointestinal side effects have included diarrhea (9%), nausea (4.1%), abdominal pain (2.2%), and dyspepsia (1.1%). Abnormal stools, anorexia, constipation, dry mouth, flatulence, vomiting, and toxic megacolon have been reported rarely.

Nervous system

Nervous system side effects have included headache (10%), dizziness (2.3%), asthenia (1.7%); paresthesia, migraine, somnolence, and nervousness.


Genitourinary side effects have included vaginitis (5.5%), dysmenorrhea (2.6%), dysuria, and menstrual disorder.


Rhinitis and pharyngitis has been reported in less than 5% of patients, although a causal relationship has not been established. Other rare, serious adverse events include angioedema.


Hypersensitivity reactions such as rash have been reported infrequently (less than 2%). One case of anaphylactic shock has been reported.


Ocular side effects have included one reported case of unilateral optic neuritis, considered possibly related to fosfomycin therapy.


Hematologic side effects have included rare reports of aplastic anemia. Transient laboratory changes have also been reported in trials: increased eosinophil count, increased or decreased WBC count, increased bilirubin, increased alkaline phosphatase, increased or decreased platelet counts, and decreased hemoglobin. Causality has not been established.


Hepatic side effects have been reported rarely and include cholestatic jaundice and hepatic necrosis. Transient increases in SGPT and SGOT have also been reported, but causality has not been established.


Respiratory side effects have been reported rarely. Exacerbation of asthma has been reported.


Dermatologic side effects have been reported rarely in clinical trials, but causality has not been established. Rash (1.4%) and skin disorders have been reported.


Musculoskeletal side effects have included reports of myalgia (less than 1%) in clinical trials. Causality has not been established.

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