What Are Cephalosporins? Uses, Warnings, Side Effects, and More

Cephalosporins are a large group of antibiotics that belong to a class known as beta-lactams. They are used to treat a wide range of bacterial infections.

These medications are bactericidal drugs, meaning they kill bacteria directly, according to Merck Manual. They do this by interfering with how bacteria build their cell walls.

Cephalosporins are grouped into five generations based on their range of coverage against bacteria and when the drugs were developed, according to an overview in StatPearls. In general, each generation is effective against different types of bacteria.

First-generation cephalosporins such as Keflex (cephalaxin) primarily work against infections that are considered easy to treat, while later-generation cephalosporins tend to be reserved for more severe bacterial infections.

Per StatPearls, cephalosporins are used to treat bacterial infections including:

• Skin infections
• Soft tissue infections
• Meningitis
• Sepsis
• Pneumonia
• Bone infections
• Sinus infections
• Lung infections
• Respiratory infections
• Urinary infections
• Biliary tract infections
• Bloodstream infections
• Ear infections
• Gonorrhea
• Lyme disease
• Staphylococcal infections

Because of their long history of development, there are numerous cephalosporins on the market. According to the Nelson Textbook of Pediatrics, the five generations of cephalosporins break down as follows:

• First-generation cephalosporins are commonly used to treat skin and soft tissue infections. Examples include cefazolin and cephalexin. Doctors also use these drugs to treat bone, respiratory, urinary, genital, biliary tract, ear, and bloodstream infections, per StatPearls.
• Second-generation cephalosporins are used to treat respiratory tract infections, UTIs, skin and soft tissue infections, and Lyme disease. Examples include cefuroxime and cefoxitin. Other second-generation cephalosporins (cefaclor, cefprozil, loracarbef, cefpodoxime) are commonly used to treat sinus, lung, and ear infections.
• Third-generation cephalosporins are typically used for serious infections, including meningitis and sepsis. Examples include ceftriaxone and ceftazidime. Ceftriaxone is also used to treat gonorrhea and Lyme disease, per StatPearls.
• A fourth-generation cephalosporin called cefepime is used to treat staphylococcal infections.
• A fifth-generation cephalosporin called ceftaroline is effective against MRSA (methicillin-resistant Staphylococcus aureus) and community-acquired pneumonia.

People who are allergic to cephalosporins, or any inactive ingredients found in these drugs, shouldn't take them.

Cephalosporins share a molecular similarity with penicillins, and so might lead to an allergic reaction in people who are allergic to penicillins. Depending on the severity of your penicillin allergy, you may still be able to take cephalosporins, but most likely not first- or second-generation drugs, notes StatPearls.

You should also avoid cephalosporins if you’ve had an anaphylactic reaction to other beta-lactams.

The third-generation cephalosporin ceftriaxone is contraindicated in some newborns, because it could increase the risk of jaundice.

Make sure your doctor or pharmacist is monitoring your kidney function when you are taking cephalosporins, because that could potentially warrant a change in the dose or dosing frequency of your medication.

An overdose of the fourth-generation cephalosporin cefepime can lead to seizures and encephalopathy (brain disease). If you have a history of seizures, especially with poor kidney function, use caution when taking cephalosporins.

As with all antibiotics, it's important that you finish the entire course you were prescribed — even if you feel better. This is the only way to ensure that the infection is completely gone. Otherwise, the infection could return and be much more difficult to treat the second time around.

Per StatPearls, the most common side effects from taking a cephalosporin are:

• Nausea
• Vomiting
• Lack of appetite
• Abdominal pain

Less common side effects include:

• Hypersensitivity or allergic reaction, including rash, hives, and swelling, and in rare cases, anaphylaxis.
• Drug-induced immune hemolytic anemia (DIIHA)
• Vitamin K deficiency
• Pseudomembranous colitis

There are reported cases of drug-induced kidney damage when people take cephalosporins in combination with aminoglycosides, another class of antibiotics, notes StatPearls.

Infants younger than 28 days old should not take ceftriaxone if they are likely to receive any calcium-containing products. Patients of all ages are advised to avoid mixing ceftriaxone and calcium-containing solutions or taking them within 48 hours of each other, per Merck Manual.

Additional reporting by Jennifer D'Angelo Friedman.

The Takeaway

Cephalosporins are versatile antibiotics used to treat various respiratory, skin, and urinary bacterial infections. Five generations of cephalosporins exist, each targeting different types of bacteria with varying effectiveness. If your doctor prescribes a cephalosporin, make sure to complete the entire course of medication to ensure the infection is fully eradicated.