Medically reviewed on April 18, 2017
What is cephalexin?
Cephalexin is a cephalosporin (SEF a low spor in) antibiotic. It works by fighting bacteria in your body.
Cephalexin is used to treat infections caused by bacteria, including upper respiratory infections, ear infections, skin infections, and urinary tract infections.
Cephalexin may also be used for purposes not listed in this medication guide.
You should not use this medicine if you are allergic to cephalexin or to similar antibiotics, such as Ceftin, Cefzil, Omnicef, and others. Tell your doctor if you are allergic to any drugs, especially penicillins or other antibiotics.
Before taking this medicine
Do not use this medicine if you are allergic to cephalexin or to other cephalosporin antibiotics, such as:
cefuroxime (Ceftin); or
cephradine (Velosef), and others.
To make sure cephalexin is safe for you, tell your doctor if you have:
an allergy to any drugs (especially penicillins);
kidney disease; or
a history of intestinal problems, such as colitis.
The liquid form of cephalexin may contain sugar. This may affect you if you have diabetes.
Cephalexin is not expected to be harmful to an unborn baby. Tell your doctor if you are pregnant.
Cephalexin can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding a baby.
How should I take cephalexin?
Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Do not use cephalexin to treat any condition that has not been checked by your doctor.
Shake the oral suspension (liquid) well just before you measure a dose. Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.
Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Cephalexin will not treat a viral infection such as the flu or a common cold.
Do not share cephalexin with another person, even if they have the same symptoms you have.
This medication can cause you to have unusual results with certain medical tests. Tell any doctor who treats you that you are using cephalexin.
Store the tablets and capsules at room temperature away from moisture, heat, and light.
Store the liquid medicine in the refrigerator. Throw away any unused liquid after 14 days.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid while taking cephalexin?
Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor. Do not use anti-diarrhea medicine unless your doctor tells you to.
Cephalexin side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
severe stomach pain, diarrhea that is watery or bloody;
jaundice (yellowing of the skin or eyes);
easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;
little or no urination;
agitation, confusion, hallucinations; or
severe skin reaction--fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Common side effects may include:
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
What other drugs will affect cephalexin?
Other drugs may interact with cephalexin, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2018 Cerner Multum, Inc. Version: 9.01.
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