Cephalexin Side Effects
Medically reviewed by Drugs.com. Last updated on Oct 2, 2023.
Applies to cephalexin: oral capsule, oral powder for suspension, oral tablet.
Serious side effects of Cephalexin
Along with its needed effects, cephalexin 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 cephalexin:
- Abdominal or stomach pain
- blistering, peeling, or loosening of the skin
- clay-colored stools
- dark urine
- general tiredness and weakness
- 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
- 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
- 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
- painful or difficult urination
- pale skin
- 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
Other side effects of Cephalexin
Some side effects of cephalexin 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:
Incidence not known
- Acid or sour stomach
- burning feeling in the chest or stomach
- difficulty with moving
- dry mouth
- irregular heartbeats
- itching of the vagina or genital area
- muscle pain or stiffness
- pain during sexual intercourse
- pain, swelling, or redness in the joints
- redness of the skin
- seeing, hearing, or feeling things that are not there
- 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.
Frequency not reported: Diarrhea, nausea, vomiting, dyspepsia, gastritis, abdominal pain, anal pruritus, Clostridium difficile-associated diarrhea/colitis/pseudomembranous colitis
Postmarketing reports: Colitis[Ref]
Frequency not reported: Transient hepatitis, cholestatic jaundice, AST and ALT elevations
Postmarketing reports: Increased bilirubin[Ref]
Allergic reactions (including urticaria and angioedema) usually subsided upon treatment discontinuation.[Ref]
Frequency not reported: Seizure, dizziness, headache[Ref]
Frequency not reported: Agitation, confusion, hallucinations[Ref]
Frequency not reported: Reversible interstitial nephritis
Postmarketing reports: Renal dysfunction, toxic nephropathy, increased blood urea nitrogen, increased creatinine[Ref]
Frequency not reported: Fatigue
Postmarketing reports: Fever[Ref]
Frequency not reported: Development of drug-resistant bacteria development[Ref]
Postmarketing reports: Increased alkaline phosphatase, increased lactate dehydrogenase (LDH)[Ref]
Postmarketing reports: Hemorrhage[Ref]
Frequently asked questions
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More about cephalexin
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- Compare alternatives
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- Reviews (494)
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- Dosage information
- Patient tips
- During pregnancy
- Support group
- Drug class: first generation cephalosporins
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Related treatment guides
1. Product Information. Keflex (cephalexin). Dista Products Company. 2002.
2. Cerner Multum, Inc. UK Summary of Product Characteristics.
3. Cerner Multum, Inc. Australian Product Information.
4. Product Information. Daxbia (cephalexin). Crown Laboratories. 2017.
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.