Cephalexin Side Effects

For the Consumer

Applies to cephalexin: oral capsule, oral powder for suspension, oral tablet, oral tablet for suspension

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

Major Side Effects

You should check with your doctor immediately if any of these side effects occur when taking cephalexin:

More common:

• Diarrhea

Rare

• Abdominal or stomach pain
• blistering, peeling, or loosening of the skin
• chills
• clay-colored stools
• cough
• dark urine
• diarrhea
• dizziness
• fever
• general tiredness and weakness
• headache
• itching or rash
• joint or muscle pain
• light-colored stools
• loss of appetite
• nausea and vomiting
• red skin lesions, often with a purple center
• red, irritated eyes
• sore throat
• sores, ulcers, or white spots in the mouth or on the lips
• unpleasant breath odor
• unusual tiredness or weakness
• upper right abdominal or stomach pain
• vomiting of blood
• yellow eyes or skin

Incidence not known:

• Abdominal or stomach cramps or tenderness
• back or leg pains
• black, tarry stools
• bleeding gums
• bloating
• blood in the urine or stools
• chest pain
• coughing up blood
• diarrhea, watery and severe, which may also be bloody
• difficulty with breathing or swallowing
• fast heartbeat
• general body swelling
• hives
• increased menstrual flow or vaginal bleeding
• increased thirst
• large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
• loss of appetite
• nosebleeds
• pain
• painful or difficult urination
• pale skin
• paralysis
• pinpoint red spots on the skin
• prolonged bleeding from cuts
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• red or black, tarry stools
• red or dark brown urine
• swollen or painful glands
• tightness in the chest
• unusual bleeding or bruising
• unusual weight loss
• watery or bloody diarrhea

Minor Side Effects

Some of the side effects that can occur with cephalexin 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:

Incidence not known:

• Acid or sour stomach
• anxiety
• belching
• burning feeling in the chest or stomach
• difficulty with moving
• dry mouth
• heartburn
• hyperventilation
• indigestion
• irregular heartbeats
• irritability
• itching of the vagina or genital area
• muscle pain or stiffness
• nervousness
• pain during sexual intercourse
• pain, swelling, or redness in the joints
• redness of the skin
• restlessness
• seeing, hearing, or feeling things that are not there
• shaking
• stomach upset
• trouble sleeping
• white or brownish vaginal discharge

For Healthcare Professionals

Applies to cephalexin: oral capsule, oral powder for reconstitution, oral tablet, oral tablet dispersible

General

The most commonly reported side effects included diarrhea, dyspepsia, gastritis, nausea, and vomiting.^[Ref]

Gastrointestinal

Frequency not reported: Diarrhea, nausea, vomiting, dyspepsia, gastritis, abdominal pain, anal pruritus, Clostridium difficile-associated diarrhea/colitis/pseudomembranous colitis
Postmarketing reports: Colitis^[Ref]

Hematologic

Frequency not reported: Direct Coombs' test seroconversion, decreased prothrombin activity/prolonged prothrombin time, eosinophilia, neutropenia, thrombocytopenia, hemolytic anemia
Postmarketing reports: Aplastic anemia, pancytopenia, leukopenia, agranulocytosis^[Ref]

Dermatologic

Frequency not reported: Urticaria, rash, erythema multiforme, Stevens Johnson syndrome, toxic epidermal necrolysis/exanthematic necrolysis^[Ref]

Hepatic

Frequency not reported: Transient hepatitis, cholestatic jaundice, AST and ALT elevations
Postmarketing reports: Increased bilirubin^[Ref]

Hypersensitivity

Frequency not reported: Hypersensitivity/allergic reactions, angioedema, anaphylaxis^[Ref]

Allergic reactions (including urticaria and angioedema) usually subsided upon treatment discontinuation.^[Ref]

Genitourinary

Frequency not reported: Genital pruritus, genital candidiasis, vulvovaginitis/vaginitis and vaginal discharge^[Ref]

Nervous system

Frequency not reported: Seizure, dizziness, headache^[Ref]

Psychiatric

Frequency not reported: Agitation, confusion, hallucinations^[Ref]

Musculoskeletal

Frequency not reported: Arthralgia, arthritis, joint disorder^[Ref]

Renal

Frequency not reported: Reversible interstitial nephritis
Postmarketing reports: Renal dysfunction, toxic nephropathy, increased blood urea nitrogen, increased creatinine^[Ref]

Other

Frequency not reported: Fatigue
Postmarketing reports: Fever^[Ref]

Immunologic

Frequency not reported: Development of drug-resistant bacteria development^[Ref]

Metabolic

Postmarketing reports: Increased alkaline phosphatase, increased lactate dehydrogenase (LDH)^[Ref]

Cardiovascular

Postmarketing reports: Hemorrhage^[Ref]

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