OpenClaim

Cephalexin Side Effects

The most commonly reported side effects of cephalexin include chronic kidney disease, drug hypersensitivity, and acute kidney injury, based on 34,649 FDA adverse event reports from 2004 to 2025. 4.3% of reports found the drug to be ineffective.

Cephalexin side effects

Percentages show how often each reaction appears relative to total reports for cephalexin.

1
Chronic Kidney Disease8.4%2,895
2
Drug Hypersensitivity6.9%2,378
3
Acute Kidney Injury5.9%2,050
4
Renal Failure5.5%1,893
5
Diarrhoea5.3%1,852
6
Fatigue5.2%1,813
7
Pain4.9%1,683
8
Nausea4.7%1,635
9
Rash4.5%1,544
10
Drug Ineffective4.3%1,490
11
Dyspnoea4.2%1,454
12
Headache4.1%1,437
13
Off Label Use4.0%1,385
14
Anxiety3.6%1,259
15
Urinary Tract Infection3.5%1,208

These are voluntary reports and do not establish that cephalexin caused these reactions.

Report severity

70.1%Serious24,306 reports
33.7%Hospitalizations11,663 reports
8.3%Fatal2,865 reports

Seriousness is determined by the reporter, not by OpenClaim.

Cephalexin drug interactions

Other drugs that appear in adverse event reports alongside cephalexin. Drugs flagged as a suspected cause appear in the first column. Drugs taken at the same time but not suspected appear in the second.

Also suspected

1
Esomeprazole7.8%2,694
2
Omeprazole7.6%2,631
3
Pantoprazole-sodium6.3%2,172
4
Lansoprazole5.5%1,913
5
Lenalidomide4.6%1,597
6
Ciprofloxacin3.0%1,042
7
Prednisone2.8%976
8
Acetaminophen2.6%886
9
Trimethoprim2.4%839
10
Adalimumab2.4%836
11
Dexlansoprazole2.4%822
12
Etanercept2.3%800
13
Amoxicillin2.3%789
14
Ethinyl-estradiol2.1%738
15
Drospirenone2.0%691

Taken alongside

1
Acetaminophen25.5%8,833
2
Aspirin16.2%5,614
3
Furosemide15.1%5,236
4
Ergocalciferol14.5%5,039
5
Prednisone14.3%4,963
6
Albuterol13.8%4,767
7
Gabapentin13.5%4,672
8
Levothyroxine-sodium12.2%4,230
9
Atorvastatin-calcium12.1%4,206
10
Omeprazole11.7%4,067
11
Ibuprofen11.7%4,040
12
Lisinopril11.6%4,033
13
Hydrocodone11.2%3,874
14
Amlodipine11.2%3,873
15
Ondansetron11.0%3,802

Co-occurrence in adverse event reports does not establish a drug interaction. Patients often take multiple medications, and these lists reflect prescribing patterns rather than causal relationships. Consult a healthcare provider about potential drug interactions.

Who reports cephalexin side effects

60.7% of cephalexin adverse event reports involve female patients and 31.8% involve male patients. The largest age group is adult at 55%. These figures reflect who reports side effects, not underlying risk.

Sex

Female60.7%
Male31.8%
Unknown7.5%

Age group

< 20.8%
2–112.0%
12–171.8%
18–6455.2%
65+40.2%

What is cephalexin used for

Conditions and purposes for which patients were taking cephalexin when the adverse event was reported.

Abdominal AbscessAbdominal DiscomfortAbdominal DistensionAbdominal PainAbdominal Pain LowerAbdominal Pain UpperAbscessAbscess LimbAbscess NeckAbscess OralAcneAcne CysticActinomycosisAcute Kidney InjuryAcute Sinusitis

Showing 15 of 1,035 indications

Cephalexin brand names and reporting trend

Cephalexin is sold under brand names including Panixine Disperdose, Keftab.

Brand names

Panixine Disperdose27,005
Keftab149

Quarterly reports (20042025)

20052010201520202025

An upward trend reflects increased FAERS reporting overall, not necessarily increased risk.

Taking cephalexin with another medication?

Ask OpenClaim about your specific drug combination. Get a sourced report using FDA data, drug labels, and medical literature.