Cephalexin

Medically reviewed by Amber Watson, PharmD on April 4, 2023
Written by Patricia Weiser, PharmD

This article describes cephalexin oral capsule’s uses and dosage, ways to save on cost, and more. Below you’ll find coupon options for cephalexin.

Cephalexin may cause mild or serious side effects. More common mild side effects of cephalexin oral capsule and its serious side effects are listed below. This article doesn’t include all possible side effects of the drug. Side effects can vary based on your age and overall health and any other medications you take.

To learn more about cephalexin oral capsule’s side effects, see this article or ask your doctor or pharmacist. You can also read the prescribing information for cephalexin oral capsule.

Mild side effects

More common mild side effects reported with cephalexin oral capsule are listed below.

With many drugs, mild side effects may go away within a few days or a couple of weeks. If the side effects are bothersome, tell your doctor or pharmacist. They may be able to suggest ways to manage them.

Cephalexin oral capsule’s mild side effects include:

• diarrhea
• nausea
• vomiting
• upset stomach
• belly pain
• mild allergic reaction*

* For details about this side effect, see the “Warnings for cephalexin” section below.

Serious side effects

Serious side effects of cephalexin oral capsule are listed below. With many drugs, serious side effects are possible but not common.

If you have serious side effects from this drug, call your doctor right away. If you’re having severe symptoms or a medical emergency, call 911 or a local emergency number.

Cephalexin oral capsule’s serious side effects include:

• Clostridioides difficile infection, which may cause severe diarrhea that’s watery or bloody
• seizures
• hallucinations (hearing or seeing things that aren’t really there)
• blood cell problems, such as low levels of red blood cells and white blood cells
• liver problems, such as swelling of your liver
• kidney problems, such as swelling of your kidneys
• severe allergic reaction*

* For details about this side effect, see the “Warnings for cephalexin” section below.

The Food and Drug Administration (FDA) approves prescription drugs such as cephalexin for certain conditions. Approved uses for cephalexin oral capsule are described below.

Use for certain infections

Doctors may prescribe cephalexin oral capsule for treating certain infections caused by bacteria. It’s used for this purpose in adults. It’s also used for this purpose in children ages 1 year and older. Cephalexin oral capsule is usually prescribed as a short-term treatment.

Specifically, cephalexin oral capsule is used to treat the following kinds of infections caused by bacteria:

• respiratory tract infection, such as a sinus infection or strep throat
• ear infection
• skin and skin tissue infection
• bone infection
• genital infection, such as gonorrhea
• urinary tract infection (UTI)

With bacterial infections, symptoms can vary depending on the kind and severity of the infection. Common signs of an infection include:

• fever
• chills
• pain in your ears or throat
• cough
• runny or stuffy nose
• a skin wound that isn’t healing
• painful urination

Below you’ll find answers to a few commonly asked questions about cephalexin oral capsule.

Is cephalexin used in dogs?

Possibly. Veterinarians sometimes prescribe human drugs for use in dogs and other animals. But it’s important not to give your dog any medications you’ve been prescribed for personal use.

Talk with your pet’s veterinarian to learn more about using cephalexin or other medications in your dog.

How does cephalexin compare with similar drugs, such as amoxicillin or ciprofloxacin?

Cephalexin, amoxicillin, and ciprofloxacin are all antibiotics. They’re each used to treat a variety of infections caused by bacteria.

Cephalexin belongs to a group of drugs called cephalosporins. Amoxicillin belongs to a group of drugs known as penicillins. And ciprofloxacin belongs to a drug group called fluoroquinolones. These antibiotics work differently to treat infections caused by different kinds of bacteria.

If you have an infection caused by bacteria, your doctor can tell you whether cephalexin, amoxicillin, ciprofloxacin, or a different antibiotic is recommended.

If you’d like to learn more about how cephalexin compares with amoxicillin or ciprofloxacin, talk with your doctor or pharmacist.

Can cephalexin be used for chlamydia?

No. Cephalexin is not used to treat chlamydia. Chlamydia is a sexually transmitted infection (STI) caused by a specific kind of bacteria called Chlamydia trachomatis. Cephalexin doesn’t work to treat this kind of bacteria.

Doctors usually prescribe other antibiotics to treat chlamydia. Common examples include doxycycline or azithromycin.

Cephalexin is used to treat other bacterial infections, including those of the genital or urinary tract. To learn more, see the “Uses of cephalexin” section above. If you have questions about the use of cephalexin, talk with your doctor or pharmacist.

How does cephalexin work? And how long does it take to start working?

Cephalexin is used to treat certain infections caused by bacteria. It works by stopping bacteria cells from making a mesh-like material that they use for protection. Without this protective material, the bacteria cells cannot survive.

Cephalexin starts working right away, but it may take a few days before you notice your symptoms easing. Be sure to finish taking all of the cephalexin your doctor prescribes, even if you feel much better before it’s all taken. Not completing the full course of treatment may prevent the drug from getting rid of your infection. It may also increase the chance of the infection coming back and making it more difficult to treat.

If you have questions about how cephalexin works, talk with your doctor or pharmacist.

Is there a best time of day to take cephalexin? What should I do if I miss a dose of cephalexin?

There isn’t a specific time of day to take cephalexin, but it’s best to take it on a consistent schedule. For example, if your doctor prescribes one dose four times a day, you could take one dose every 6 hours. An example schedule of this dosing might be:

• dose one at 5 a.m.
• dose two at 11 a.m.
• dose three at 5 p.m.
• dose four at 11 p.m.

In general, it’s safe to take each dose an hour or so before or after it’s due. The important thing is to take all of the doses your doctor prescribes and finish the full length of treatment.

If you miss a dose of cephalexin, take it as soon as possible. Skipping doses or not completing the full length of treatment may prevent the drug from getting rid of your infection. It may also increase the risk of the infection coming back and make it more difficult to treat.

Talk with your doctor or pharmacist if you have questions about when to take your cephalexin dose.

Can cephalexin capsules be crushed, split, or chewed?

Cephalexin capsules should not be crushed, split, or chewed.

If you have trouble swallowing pills, talk with your doctor or pharmacist. They may suggest you take the cephalexin oral suspension (a kind of liquid mixture) instead of the oral capsule. Talk with your doctor or pharmacist if you have questions about cephalexin oral suspension.

The dosage of cephalexin oral capsule your doctor prescribes may vary based on your condition and certain other factors. Talk with your doctor about the dosage you should take.

Taking cephalexin

Cephalexin oral capsule is swallowed. It can be taken with or without food.

Your doctor will talk with you about how to take cephalexin oral capsule. They’ll explain how much to take and how often. Always follow your doctor’s recommendation.

See the “Common questions about cephalexin” section above for information on missed doses and the best time to take this drug.

Overdose of cephalexin

You should not take more cephalexin than your doctor prescribes. For some drugs, doing so may lead to serious side effects or overdose.

If you think you’ve taken too much cephalexin, call your doctor or pharmacist right away. Or you could call 800-222-1222 to speak with someone at America’s Poison Centers. You can also use its online resource. If you have concerning symptoms, call 911 or a local emergency number immediately. You can also go to the closest emergency room.

For some medications, certain things may affect how the drug works. These include getting vaccines, consuming alcohol or certain foods, or taking the drug with other medications. This effect is called a drug interaction.

Before you take cephalexin, ask your doctor to check for possible interactions. They can check for interactions these items may cause with cephalexin. Be sure to tell them about any of the following you take or use:

• prescription medications
• over-the-counter medications
• vitamins, herbs, or supplements

To learn about drug-condition interactions, see the “Warnings for cephalexin” section below.

Information about cephalexin and pregnancy and breastfeeding is described below.

Cephalexin and pregnancy

In general, cephalexin oral capsule is considered safe to take during pregnancy. That said, check with your doctor about whether they feel it’s safe for you specifically.

Cephalexin and breastfeeding

It isn’t known whether cephalexin is safe to take while breastfeeding. The drug passes into breast milk. There have been rare reports of side effects, such as diarrhea in a child who is breastfed. Talk with your doctor about whether they feel it’s safe for you to take cephalexin specifically.

You may be able to save money on your prescription for cephalexin oral capsule by using our Perks discount coupons. These can be found at the end of this article.

If you have questions about how to pay for cephalexin, talk with your doctor or pharmacist. You can also learn more about the cost of cephalexin in this article.

Note: Optum Perks coupons cannot be used with insurance copays or benefits.

Cephalexin should be used with caution in certain people. Precautions for taking this drug are described below.

Warnings

Cephalexin could cause harm to people with certain health conditions. This effect is called a drug-condition interaction. Other factors can also affect whether cephalexin oral capsule is a safe option for you.

Tell your doctor about your overall health and any past health conditions before you take cephalexin oral capsule. Health conditions and other factors you and your doctor should discuss include:

• nutritional deficiencies, which may be the result of eating habits
• liver problems
• kidney problems
• seizure disorder

Allergic reaction

Cephalexin can cause an allergic reaction in some people. Severe allergic reactions are rare but possible.

If you’ve had an allergic reaction to cephalexin or any of its ingredients, your doctor will likely not prescribe cephalexin. Also, if you’ve had an allergic reaction to any medication that belongs to the cephalosporin or penicillin groups of drugs, your doctor may not prescribe cephalexin. This is because some people who are allergic to other cephalosporins or penicillins may also have an allergic reaction to cephalexin. (Cephalexin is a kind of cephalosporin drug.) Your doctor can tell you about medications that may be safer options for you.

A mild allergic reaction may cause the following symptoms:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)

A severe allergic reaction may cause the following symptoms:

• swelling under your skin, usually in your hands, feet, eyelids, or lips
• swelling of your mouth, throat, or tongue, which can cause breathing problems

If you have an allergic reaction to cephalexin, call your doctor right away. If you have severe symptoms, call 911 or a local emergency number.

This article describes cephalexin oral capsule’s uses and dosage, ways to save on cost, and more. Let your doctor know if you have questions about cephalexin or would like more details about it.

Here’s a list of some possible questions you may want to ask your doctor:

• Should I continue taking my vitamins and supplements during cephalexin treatment?
• Do I need to use a certain backup birth control method while taking cephalexin?
• Should I take any certain over-the-counter drugs to manage the symptoms of my infection while taking cephalexin?

• Cephalexin. (2021). https://www.ncbi.nlm.nih.gov/books/NBK501487/
• Cephalexin capsules, for oral use. (2023). https://nctr-crs.fda.gov/fdalabel/services/spl/set-ids/d3527c0a-94e4-46a2-be77-d936abcd19ec/spl-doc
• Chlamydial infections. (2021). https://www.cdc.gov/std/treatment-guidelines/chlamydia.htm
• Food and Drug Administration. (2023). Orange Book: Approved drug products with therapeutic equivalence evaluations. https://www.accessdata.fda.gov/scripts/cder/ob/index.cfm

Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.