Cephalexin

Common Uses

Cephalexin is a cephalosporin antibiotic prescribed to treat infections caused by specific types of bacteria. It works by preventing the growth of the bacterial cell wall, which eventually kills the bacteria. Common conditions treated with this medication include:

• Respiratory tract infections: This includes infections such as pneumonia and tonsillitis (strep throat).
• Ear infections: It is frequently used to treat middle ear infections, also known as otitis media.
• Skin and soft tissue infections: It treats various bacterial infections of the skin and the structures just beneath the skin.
• Bone infections: It may be used to treat infections that have spread to or originated in the bones.
• Genitourinary tract infections: This includes infections of the urinary tract, such as cystitis (bladder infection) and prostatitis.

Important Limitations

Cephalexin is only effective against bacterial infections. It will not work for viral infections, such as the common cold, the flu, or most cases of bronchitis. Taking antibiotics when they are not needed increases the risk of developing an antibiotic-resistant infection later on.

Mechanism of Action

Cephalexin belongs to a group of medicines called cephalosporin antibiotics. It works by interfering with the way bacteria build their cell walls.

Bacteria require a sturdy outer wall to protect themselves from their environment and to keep their internal contents together. Cephalexin binds to specific proteins within the bacterial cell wall, preventing the bacteria from completing the construction of this protective layer. As a result, the cell wall becomes weak and unstable, causing the bacteria to rupture and die.

Targeting Infections

This medication is considered bactericidal, meaning it actively kills bacteria rather than just slowing their growth. It is effective against a variety of common bacteria that cause infections in different parts of the body, including the skin, ears, respiratory tract, and urinary tract.

Because cephalexin specifically targets the structure of bacterial cell walls—which human cells do not have—it can eliminate the infection while leaving the patient's cells intact. It is important to remember that this drug only treats bacterial infections and is not effective against viruses, such as those that cause the common cold or flu.

Common Side Effects

Many people taking cephalexin do not experience significant side effects. When they do occur, common symptoms may include:

• Nausea or vomiting
• Diarrhea
• Stomach pain or heartburn
• Genital itching or discharge
• Dizziness or extreme tiredness

Serious Side Effects

Contact a healthcare provider immediately if you experience any of the following serious symptoms:

• Signs of an allergic reaction, such as a skin rash, hives, itching, or swelling of the face, lips, tongue, or throat
• Difficulty breathing or swallowing
• Severe stomach cramps or watery or bloody diarrhea, which may occur during treatment or up to several months after the last dose
• Fever, sore throat, or joint pain
• Yellowing of the eyes or skin (jaundice)
• Dark-colored urine
• Unusual bruising or bleeding

This is not a complete list of side effects. If you notice other unusual symptoms while taking this medication, consult your doctor or pharmacist.

Allergic Reactions

Serious and potentially life-threatening allergic reactions, including anaphylaxis, can occur. Individuals with a known allergy to cephalexin or other cephalosporin antibiotics should not use this medication. Because of the risk of cross-sensitivity, caution is necessary for those with a history of penicillin allergy, as some patients may react to both types of antibiotics.

Diarrhea and Colitis

Treatment with cephalexin can change the normal bacteria in the gut, potentially leading to an overgrowth of Clostridioides difficile. This can cause Clostridioides difficile-associated diarrhea (CDAD), which ranges from mild diarrhea to severe, life-threatening inflammation of the colon. This condition may occur during treatment or several months after the medication is stopped.

Kidney Function and Seizures

For individuals with decreased kidney function, the dosage may need adjustment by a healthcare provider. There is an increased risk of seizures if high doses are administered to those with renal impairment without proper dose reduction.

Laboratory Tests

Cephalexin may cause a false-positive result on a direct Coombs' test, which is used to detect certain blood conditions. It may also cause false-positive results in urine glucose tests using specific reagents, such as Benedict's solution or Fehling's solution.

General Precautions

• Prolonged use of cephalexin may result in the overgrowth of nonsusceptible organisms, such as fungi or other bacteria.
• The medication should only be used to treat infections that are proven or strongly suspected to be caused by bacteria to help prevent the development of drug-resistant bacteria.

Pregnancy

Cephalexin is frequently used during pregnancy and is generally considered to have a low risk of causing harm to the developing fetus. Animal reproduction studies have shown no evidence of impaired fertility or harm to the fetus. However, because there are no adequate and well-controlled studies in pregnant humans, healthcare providers typically recommend using this medication during pregnancy only when it is clearly needed.

Breastfeeding

Cephalexin passes into breast milk in small amounts. While it is generally considered compatible with breastfeeding, there are a few considerations for nursing parents:

• The medication is usually not expected to cause serious side effects in a nursing infant.
• Exposure to antibiotics through breast milk may occasionally cause changes in the infant's gut bacteria, potentially leading to diarrhea or diaper rash.
• There is a small possibility of the infant developing a fungal infection, such as oral thrush, or an allergic reaction.

If you are breastfeeding, it is important to discuss the use of cephalexin with a healthcare provider to weigh the benefits of treatment against any potential risks to the infant.

Available Forms

Cephalexin is primarily administered by mouth and is available in the following formats:

• Capsules: A common oral form that is swallowed whole.
• Tablets: Solid oral tablets that are swallowed whole.
• Powder for Oral Suspension: This form is reconstituted with water by a pharmacist to create a liquid medication. It is typically used for pediatric patients or individuals who have difficulty swallowing solid pills.

FDA Approval and Indications

Cephalexin is a prescription medication approved by the U.S. Food and Drug Administration (FDA) for the treatment of specific infections caused by susceptible strains of bacteria. Approved uses include:

• Respiratory tract infections
• Otitis media (middle ear infections)
• Skin and skin structure infections
• Bone infections
• Genitourinary tract infections, including acute prostatitis

Regulatory Status

Cephalexin was originally approved by the FDA in 1971. It is currently available as a generic medication in several oral forms, including capsules, tablets, and oral suspensions. The FDA has determined that this medication is safe and effective when used according to the professional labeling for its approved indications.

Safety Communications

Cephalexin does not carry a Boxed Warning, which is the FDA's most serious warning for significant safety risks. It is also not subject to a Risk Evaluation and Mitigation Strategy (REMS) program. While the FDA has issued safety communications for other antibiotic classes, such as fluoroquinolones, regarding risks like aortic ruptures or permanent disabling side effects, these specific warnings do not apply to cephalexin.

Alcohol and Cephalexin

Currently, there are no specific warnings or known drug interactions between cephalexin and alcohol. Unlike certain other antibiotics, cephalexin does not typically cause a severe reaction if alcohol is consumed during treatment.

General Considerations

While there is no direct interaction, healthcare providers often suggest avoiding or limiting alcohol while taking antibiotics for several reasons:

• Side Effects: Both cephalexin and alcohol can cause side effects like nausea, vomiting, and dizziness. Combining them may increase the likelihood or severity of these symptoms.
• Immune System Support: Alcohol can interfere with the body's ability to fight off infections and may lead to dehydration or poor sleep, which can slow the healing process.
• Stomach Irritation: Cephalexin can sometimes cause stomach upset. Alcohol is also a known stomach irritant, and using both together might increase gastrointestinal discomfort.

If you have questions about consuming alcohol while taking this medication, it is best to consult with a doctor or pharmacist to ensure it is safe for your specific health situation.