Cephalexin Side Effects

The more common side effects of cephalexin are listed below. Tell your doctor if these side effects are severe or continue after a few days:

• Gastrointestinal symptoms such as heartburn, stomach pain, nausea, vomiting, diarrhea 
• Dizziness
• Tiredness
• Itching in the rectal or genital area
• Headache
• Joint pain
• Confusion
• Agitation

Some of the possible side effects of cephalexin can be more serious. Contact your doctor for medical advice immediately or get emergency medical help if you develop the following symptoms:

• Skin rash, hives, itching, blistering
• Swelling of the face, eyes, lips, mouth, or throat
• Wheezing
• Trouble breathing or swallowing
• Watery, bloody, or foul-smelling diarrhea with or without fever, severe stomach pain, and stomach cramps (up to 2 months or more after finishing antibiotics)
• Recurrent signs of infection, including flu-like symptoms such as fever, chills, sore throat
• Hallucinations (seeing or hearing things that are not there)

The above list may not include all the potential adverse effects of cephalexin. Contact your healthcare professional if the side effects are unusual or severe or they do not get better over time. You can also report unusual side effects to the Food and Drug Administration at 1-800-FDA-1088.

Cephalexin Overdose: In case of an overdose, call your doctor immediately. You can also call your local poison control center or the national poison control center at 1-800-222-1222. Call 911 if a person cannot be awakened, has trouble breathing, has collapsed, or has had a seizure. Signs and symptoms of a cephalexin overdose may include stomach pain, nausea, vomiting, diarrhea, and urine that is red, pink, or dark brown in color.

Source: FDA