What is Cephalexin: Uses, Dosage, Side Effects and More

Cephalexin is a prescription antibiotic that fights bacterial infections in your body. It belongs to a group of medicines called cephalosporins, which work by stopping bacteria from building their protective walls. This medication is commonly prescribed for skin infections, respiratory tract infections, and urinary tract infections that don't respond to milder antibiotics.

What is Cephalexin?

Cephalexin is a semi-synthetic antibiotic that your doctor prescribes to treat various bacterial infections. It's what we call a first-generation cephalosporin antibiotic, meaning it's been around for decades and has a well-established safety profile. Think of it as a reliable, well-tested tool in your doctor's antibiotic toolkit.

This medication comes in several forms including capsules, tablets, and liquid suspension for children or adults who have trouble swallowing pills. The generic name is cephalexin, but you might see it sold under brand names like Keflex. It's only available with a prescription because antibiotics need medical supervision to ensure they're used safely and effectively.

What is Cephalexin Used For?

Cephalexin treats bacterial infections in different parts of your body when other antibiotics might not be strong enough. Your doctor will typically prescribe it for infections that need a moderate-strength antibiotic to clear up completely.

The most common infections that cephalexin helps treat include several types that you might encounter in everyday life:

• Skin and soft tissue infections like cellulitis, impetigo, or infected wounds
• Respiratory tract infections including pneumonia, bronchitis, and throat infections
• Urinary tract infections (UTIs) affecting your bladder or kidneys
• Bone and joint infections, particularly in cases where the infection has spread deeper
• Middle ear infections (otitis media) that haven't responded to first-line treatments

Sometimes doctors prescribe cephalexin for less common infections like endocarditis (heart valve infection) or as preventive treatment before certain dental or surgical procedures. Your healthcare provider will determine if cephalexin is right for your specific situation based on the type of bacteria causing your infection.

How Does Cephalexin Work?

Cephalexin works by disrupting the way bacteria build and maintain their cell walls. It's considered a moderately strong antibiotic that targets the construction process bacteria use to protect themselves. When bacteria can't build proper cell walls, they become weak and eventually die off.

This medication is what we call bactericidal, meaning it actually kills bacteria rather than just stopping them from growing. It's particularly effective against common bacteria like Staphylococcus, Streptococcus, and certain types of E. coli. However, it doesn't work against viral infections like the common cold or flu, which is why your doctor will only prescribe it for confirmed or strongly suspected bacterial infections.

The strength of cephalexin falls somewhere in the middle range of antibiotics. It's stronger than basic antibiotics like amoxicillin for certain infections, but not as powerful as some of the newer, broader-spectrum antibiotics that doctors reserve for more serious infections.

How Should I Take Cephalexin?

Take cephalexin exactly as your doctor prescribes it, typically every 6 to 12 hours depending on your specific infection and dosage. You can take it with or without food, but taking it with a meal or snack can help prevent stomach upset if you're sensitive to medications.

Swallow the capsules or tablets whole with a full glass of water. If you're taking the liquid form, measure it carefully with the measuring spoon or cup that comes with the medication. Don't use regular household spoons because they don't give accurate measurements. Shake the liquid well before each dose to ensure the medication is evenly distributed.

It's important to space your doses evenly throughout the day to maintain steady levels of the antibiotic in your system. If you're taking it twice daily, try to take it every 12 hours. For three times daily, aim for every 8 hours. Setting phone reminders can help you stay on track with your dosing schedule.

Continue taking cephalexin for the full course your doctor prescribed, even if you start feeling better after a few days. Stopping early can allow bacteria to survive and potentially develop resistance to the antibiotic.

How Long Should I Take Cephalexin For?

Most people take cephalexin for 7 to 14 days, but your specific treatment length depends on the type and severity of your infection. Your doctor will determine the right duration based on factors like where the infection is located, how serious it is, and how quickly you respond to treatment.

For simple skin infections or mild urinary tract infections, you might only need a 7-day course. More serious infections like pneumonia or bone infections typically require 10 to 14 days of treatment. In some cases, particularly severe infections might need longer treatment periods.

Never stop taking cephalexin early, even if you feel completely better. Bacteria can still be present in your system even when symptoms disappear, and stopping too soon can lead to the infection coming back stronger. If you experience concerning side effects, contact your doctor rather than stopping the medication on your own.

What Are the Side Effects of Cephalexin?

Most people tolerate cephalexin well, but like all medications, it can cause side effects in some individuals. The good news is that serious side effects are relatively uncommon, and most people experience only mild, temporary effects if any at all.

Common side effects that affect some people include digestive issues that usually resolve as your body adjusts to the medication:

• Nausea or stomach upset
• Diarrhea or loose stools
• Stomach pain or cramping
• Vomiting
• Headache
• Dizziness

These common side effects are generally mild and often improve after the first few days of treatment. Taking the medication with food can help reduce stomach-related side effects.

Less common but more serious side effects require immediate medical attention. While rare, these can include signs of allergic reactions or severe complications:

• Severe diarrhea that may contain blood or mucus (could indicate C. diff infection)
• Skin rash, hives, or itching
• Difficulty breathing or swallowing
• Swelling of face, lips, tongue, or throat
• Severe stomach pain or cramping
• Yellowing of skin or eyes

Contact your doctor right away if you experience any of these more serious side effects, especially signs of allergic reactions or severe digestive problems.

Who Should Not Take Cephalexin?

Cephalexin isn't suitable for everyone, and your doctor will review your medical history before prescribing it. People with certain allergies or medical conditions may need alternative antibiotics to ensure their safety.

You should not take cephalexin if you're allergic to cephalosporin antibiotics or have had severe reactions to similar medications in the past. If you have a penicillin allergy, tell your doctor because there's a small chance of cross-reactivity, though many people with penicillin allergies can safely take cephalexin.

Certain medical conditions require special consideration before starting cephalexin. Your doctor will need to know about these conditions to adjust your treatment or monitor you more closely:

• Kidney disease or reduced kidney function
• History of colitis or severe digestive problems
• Liver disease
• History of seizures
• Pregnancy or breastfeeding

If you have kidney problems, your doctor might prescribe a lower dose or monitor your kidney function during treatment. Pregnant and breastfeeding women can usually take cephalexin safely, but your doctor will weigh the benefits against any potential risks.

Cephalexin Brand Names

Cephalexin is available under several brand names, with Keflex being the most well-known. Other brand names include Biocef, Keftab, and Panixine DisPertab, though availability varies by country and pharmacy.

The generic version of cephalexin works just as effectively as brand-name versions and typically costs less. Most insurance plans prefer the generic version, and pharmacies often stock it as their primary option. Whether you receive generic cephalexin or a brand-name version, the active ingredient and effectiveness remain the same.

Cephalexin Alternatives

Several other antibiotics can treat similar infections if cephalexin isn't right for you or doesn't work effectively for your specific situation. Your doctor might consider alternatives based on your medical history, the type of bacteria causing your infection, or previous treatment responses.

Common alternatives include other antibiotics that work against similar bacteria but have different mechanisms of action or side effect profiles:

• Amoxicillin or amoxicillin-clavulanate for milder infections
• Clindamycin for skin and soft tissue infections
• Azithromycin for respiratory tract infections
• Trimethoprim-sulfamethoxazole for urinary tract infections
• Other cephalosporins like cefdinir or cefuroxime

Your doctor will choose the best alternative based on culture results when available, your allergy history, and the specific location and severity of your infection. Never switch antibiotics on your own, as different antibiotics target different bacteria and may not be effective for your particular infection.

Is Cephalexin Better Than Amoxicillin?

Cephalexin and amoxicillin are both effective antibiotics, but neither is universally better than the other. The choice between them depends on the specific bacteria causing your infection, your medical history, and how well each medication works against the particular strain you're dealing with.

Cephalexin tends to be more effective against certain types of skin infections and some antibiotic-resistant bacteria that don't respond well to amoxicillin. It's also a good choice for people who have had recurring infections that haven't fully cleared with amoxicillin in the past.

Amoxicillin, on the other hand, is often preferred for respiratory tract infections, ear infections, and certain types of urinary tract infections. It's generally considered gentler on the stomach and is often the first choice for children with common infections.

Your doctor will choose the antibiotic most likely to clear your specific infection based on factors like the location of the infection, local resistance patterns, and your individual response to antibiotics in the past.