In this drug factsheet:
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- mild diarrhea
- mild stomach cramps
- sore mouth or tongue
- vaginal itching or discharge
Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- abdominal tenderness
- convulsions (seizures)
- decrease in urine output
- hearing loss (young children)
- joint pain
- severe abdominal or stomach cramps and pain
- signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
- skin rash, itching, redness, or swelling
- unusual bleeding or bruising
- unusual tiredness or weakness
Stop taking the medication and seek immediate medical attention if any of the following occur:
- diarrhea (watery and severe; may also be bloody)
- fever that appears after starting the antibiotic
- signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
- signs of a severe skin reaction (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Allergy: Some people who are allergic to penicillin antibiotics also experience allergic reactions to cephalosporins, including cephalexin. Before you take cephalexin, inform your doctor about any previous adverse reactions you have had to medications, especially cephalosporins and penicillins. Contact your doctor at once if you experience signs of an allergic reaction, such as skin rash, itching, difficulty breathing, or swelling of the face and throat.
Antibiotic-associated colitis: This medication, like other antibiotics, may cause a potentially dangerous condition called antibiotic-associated colitis (or pseudomembranous colitis). Symptoms include severe, watery diarrhea that may be bloody. If you notice these symptoms, stop taking cephalexin and contact your doctor as soon as possible.
Kidney function: People with severe kidney problems may require a lower dose of cephalexin. People with kidney disease or reduced kidney function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver function: Cephalexin can cause a decrease in liver function, although this happens only occasionally. People with liver disease or reduced liver function should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you experience signs of decreasing liver function, such as yellowing of the skin or whites of the eyes, dark urine, or pale stools, contact your doctor as soon as possible.
Overgrowth of organisms: Prolonged or repeated use of cephalexin may result in an overgrowth of bacteria or fungi and organisms that are not killed by the medication. This can cause other infections to develop, such as yeast infections.
Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.
Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking cephalexin, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
What other drugs could interact with this medication?
There may be an interaction between cephalexin and any of the following:
- tuberculosis vaccine
- typhoid vaccine
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.