Omnicef Side Effects

Generic name: cefdinir

Medically reviewed by Drugs.com. Last updated on Aug 8, 2023.

Note: This document provides detailed information about Omnicef Side Effects associated with cefdinir. Some dosage forms listed on this page may not apply specifically to the brand name Omnicef.

Applies to cefdinir: oral capsule, oral powder for suspension.

Serious side effects of Omnicef

Along with its needed effects, cefdinir (the active ingredient contained in Omnicef) 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 cefdinir:

More common

• diarrhea

Rare

• black, tarry stools
• chest pain
• chills
• cough
• fever
• painful or difficult urination
• shortness of breath
• sore throat
• sores, ulcers, or white spots on the lips or in the mouth
• swollen glands
• unusual bleeding or bruising
• unusual tiredness or weakness

Incidence not known

• abdominal or stomach cramps or tenderness
• back, leg, or stomach pains
• bleeding gums
• blistering, peeling, or loosening of the skin
• bloating
• blood in the urine or stools
• bloody nose
• bloody or cloudy urine
• bloody, black, or tarry stools
• blue lips, fingernails, or skin
• bruising
• chest pain or discomfort
• clay-colored stools
• cold, clammy skin
• confusion
• coughing or vomiting blood
• cracks in the skin
• dark-colored urine
• diarrhea, watery and severe, which may also be bloody
• difficult or troubled breathing
• difficulty with breathing or swallowing
• dilated neck veins
• dizziness
• extreme fatigue
• fast heartbeat
• fast, weak pulse
• feeling of discomfort
• general body swelling
• general tiredness and weakness
• headache
• heavier menstrual periods
• high fever
• hives
• hoarseness
• increased thirst
• inflammation of the joints
• irregular breathing
• irregular heartbeat
• irregular, fast or slow, or shallow breathing
• itching
• joint or muscle pain
• light-colored stools
• lightheadedness
• loss of appetite
• loss of consciousness
• loss of heat from the body
• muscle aches
• muscle cramps or spasms
• muscle pain or stiffness
• nausea or vomiting
• noisy breathing
• nosebleeds
• pain in the ankles or knees
• pain or discomfort in the arms, jaw, back, or neck
• painful, red lumps under the skin, mostly on the legs
• pale skin
• persistent bleeding or oozing from puncture sites, mouth, or nose
• pinpoint red spots on the skin
• problems with bleeding or clotting
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• rash
• red skin lesions, often with a purple center
• red, irritated eyes
• red, swollen skin
• scaly skin
• seizures
• severe stomach pain
• slow or irregular breathing
• sudden decrease in the amount of urine
• sweating
• swelling of the face, fingers, feet, or lower legs
• swollen lymph glands
• tightness in the chest
• unpleasant breath odor
• unusual weight loss
• upper right abdominal or stomach pain
• vomiting of blood
• weight gain
• wheezing
• yellow eyes or skin

Other side effects of Omnicef

Some side effects of cefdinir 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:

Less common

• itching of the vagina or genital area
• pain during sexual intercourse
• thick, white vaginal discharge with no odor or with a mild odor
• vaginal yeast infection

Rare

• acid or sour stomach
• belching
• constipation
• dry mouth
• excess air or gas in the stomach or intestines
• full feeling
• heartburn
• increase in body movements
• increased clear or white vaginal discharge
• indigestion
• lack or loss of strength
• passing gas
• rash with flat lesions or small raised lesions on the skin
• sleepiness or unusual drowsiness
• soreness or redness around the fingernails and toenails
• stomach discomfort, upset, or pain
• unable to sleep

Incidence not known

• burning, dry, or itching eyes
• discharge, excessive tearing
• redness, pain, or swelling of the eye, eyelid, or inner lining of the eyelid
• swelling or inflammation of the mouth

For healthcare professionals

Applies to cefdinir: oral capsule, oral powder for reconstitution.

Gastrointestinal

Gastrointestinal side effects have included diarrhea (15%), nausea (3%), abdominal pain (1%), dyspepsia (0.7%), flatulence (0.7%), vomiting (0.7%), anorexia (0.3%), constipation (0.3%), dry mouth (03%), abnormal stools (0.3%), moniliasis (0.2%) and pseudomembranous colitis. Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included stomatitis, acute enterocolitis, bloody diarrhea, hemorrhagic colitis, melena, upper GI bleed, peptic ulcer, and ileus.^[Ref]

Reddish-colored stools have occurred when cefdinir was taken with iron-containing products, and may be due to the formation of non-absorbable complexes in the GI tract.^[Ref]

Hypersensitivity

Hypersensitivity reactions associated with cephalosporin class antibiotics have included allergic reactions, anaphylaxis, Stevens-Johnson syndrome, erythema multiforme, and toxic epidermal necrolysis. Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included anaphylaxis (with rare cases of fatality), serum sickness-like reactions, Stevens-Johnson syndrome, and toxic epidermal necrolysis.^[Ref]

Dermatologic

Dermatologic side effects have included rash (0.9%) and pruritus (0.2%). Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included exfoliative dermatitis, erythema multiforme, and erythema nodosum.^[Ref]

Genitourinary

Genitourinary side effects have included vaginal moniliasis (4% of women), vaginitis (1% of women), leukorrhea (0.2% of women), increased urine leukocytes (2%), increased urine protein (1%), increased microhematuria (1%), increased urine glucose (0.9%), increased urine specific gravity (0.6%), decreased urine specific gravity (0.2%), increased urine pH (0.2%). Cephalosporins as a class have been associated with false-positive tests for urine glucose.^[Ref]

Nervous system

Nervous system side effects have included headache (2%), dizziness (0.3%), insomnia (0.2%), asthenia (0.2%), and somnolence (0.2%). Some cephalosporins have been associated with seizures in renally impaired patients. Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included loss of consciousness.^[Ref]

Hematologic

Hematologic side effects have included increased lymphocytes (1%), decreased lymphocytes (0.2%), increased white blood cells (0.9%), decreased white blood cells (0.7%), increased eosinophils (0.7%), decreased hemoglobin (0.3%), increased polymorphonuclear neutrophils (0.3%), decreased polymorphonuclear neutrophils (0.2%), and increased platelets (0.2%). Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included granulocytopenia, pancytopenia, leukopenia, thrombocytopenia, idiopathic thrombocytopenic purpura, hemolytic anemia, bleeding tendency, coagulation disorder, and disseminated intravascular coagulation. Cephalosporins as a class have been associated with aplastic anemia, hemolytic anemia, prolonged prothrombin time, hemorrhage, neutropenia, pancytopenia, and agranulocytosis.^[Ref]

Metabolic

Metabolic side effects have included increased gamma-glutamyltransferase (1%), increased alanine aminotransferase (0.7%), decreased bicarbonate (0.6%), increased phosphorus (0.6%), decreased phosphorus (0.3%), increased aspartate aminotransferase (0.4%), increased alkaline phosphatase (0.3%), increased blood urea nitrogen (0.3%), increased bilirubin (0.2%), increased lactate dehydrogenase (0.2%), and increased potassium (0.2%).^[Ref]

Hepatic

Hepatic side effects associated with cephalosporins as a class have included hepatic dysfunction, including cholestasis. Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included acute hepatitis, cholestasis, fulminant hepatitis, hepatic failure, jaundice, and increased amylase.^[Ref]

Renal

Renal side effects associated with cephalosporins as a class have included renal dysfunction and toxic nephropathy. Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included acute renal failure and nephropathy.^[Ref]

Ocular

Ocular adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included conjunctivitis.^[Ref]

Respiratory

Respiratory adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included acute respiratory failure, asthmatic attack, drug-induced pneumonia, eosinophilic pneumonia, and idiopathic interstitial pneumonia.^[Ref]

Other

Adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included fever, shock, feeling of suffocation, and facial and laryngeal edema.^[Ref]

Cardiovascular

Cardiovascular adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included cardiac failure, chest pain, myocardial infarction, hypertension, and allergic vasculitis.^[Ref]

Musculoskeletal

Musculoskeletal adverse effects reported during postmarketing experience with cefdinir (the active ingredient contained in Omnicef) regardless of causality, have included involuntary movements and rhabdomyolysis.^[Ref]

Other

Geriatric patients have been reported to experience a lower rate of adverse events, including diarrhea, than younger patients.^[Ref]

Frequently asked questions

• Cefdinir - Can a capsule be broken open and sprinkled on food?

Further information

Omnicef side effects can vary depending on the individual. 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.

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