Cephalexin 500 mg is a widely prescribed antibiotic used to treat a range of bacterial infections in adults and children. Marketed under the brand name Keflex, this medication belongs to the cephalosporin class of antibiotics, which are known for their effectiveness against Gram-positive bacteria. Whether you’re taking a green capsule labeled 219, a red capsule marked Teva 3147, or a white pill, each variation of cephalexin works similarly to combat infection. But what exactly is cephalexin 500 mg used for, and is it considered a strong antibiotic?

What Is Cephalexin 500 mg Used For?

Cephalexin 500 mg capsules are commonly used to treat various infections, including:

• Urinary Tract Infections (UTIs) – Cephalexin for UTI is a frequent prescription, particularly effective in women. The standard cephalexin dosage for adults with UTIs is often 500 mg every 6 to 8 hours.
  
  
• Sinus Infections – While not always a first-line treatment, cephalexin 500 mg for sinus infection can be prescribed when other antibiotics are unsuitable. Keflex for sinus infection has shown success when used under the right clinical guidance.
  
  
• Ear Infections – Cephalexin for ear infection is especially useful in pediatric and adult cases when bacteria are the confirmed cause.
  
  
• Skin and Soft Tissue Infections – Cellulitis and abscesses are commonly treated with cephalexin 500 mg capsules, particularly in non-MRSA cases.
  
  
• Tooth and Gum Infections – Dentists sometimes prescribe cephalexin 500 mg for tooth infection, especially if the patient is allergic to penicillin.
  
  
• Sexually Transmitted Infections (STIs) – Though not a first choice, cephalexin for STDs like gonorrhea is sometimes considered when no other options are available.
  
  

Cephalexin 250 mg and cephalexin 750 mg are also available, depending on the severity of the infection and patient needs. Pediatric suspensions and cephalexin tablets are available for children and those who can’t swallow capsules.

How Cephalexin Works

Cephalexin is a bactericidal antibiotic, meaning it kills bacteria by interfering with the synthesis of the bacterial cell wall. This mechanism of action is similar to penicillin, although cephalexin is not a penicillin drug. However, people with penicillin allergies should still exercise caution.

It’s often considered a strong antibiotic in the context of mild to moderate infections, especially due to its broad-spectrum activity. While it isn’t the most potent antibiotic available, asking “is cephalexin 500 mg a strong antibiotic?” is valid—because for many common infections, the answer is yes.

Cephalexin Dosage for Adults and Children

The cephalexin 500mg dosage for adults varies depending on the type and severity of the infection:

• For UTIs: 500 mg every 6 hours for 7–14 days is typical.
  
  
• For skin infections: 500 mg 4 times a day.
  
  
• For sinus infections: Dosage may be 500 mg 3–4 times daily.
  
  

Children are usually prescribed cephalexin oral suspension based on weight. Cephalexin 250 mg/5ml susp dosage for child varies, and pediatricians should determine the exact quantity.

If you see a green capsule labeled 219 or a red capsule marked Teva 3147, you’re likely holding cephalexin 500 mg. These markings help pharmacists and patients identify the generic cephalexin brand names like Lupin or Teva. The brand Keflex is often more expensive but pharmacologically identical to the generics.

Side Effects of Cephalexin 500 mg

Like all antibiotics, cephalexin comes with possible side effects. The most common include:

• Diarrhea
  
  
• Nausea or vomiting
  
  
• Headache
  
  
• Rash
  
  
• Vaginal yeast infection
  
  

More serious side effects, though rare, include allergic reactions like hives or anaphylaxis. Ask your doctor if cephalexin contains sulfa if you have a sulfa allergy—note, cephalexin is not a sulfa drug.

Cephalexin and Yeast Infections

A frequently asked question is: does cephalexin cause yeast infection? Because it disrupts normal bacterial flora, cephalexin can lead to an overgrowth of yeast. In such cases, antifungal treatment may be required.

Interestingly, cephalexin is sometimes explored for off-label uses like yeast infections, but it is not a standard treatment. Still, people often wonder: “Can cephalexin treat yeast infection?” The answer is no, it treats bacterial—not fungal—infections.

Cephalexin vs. Keflex: Is There a Difference?

Keflex is simply a brand name for cephalexin. The medication is available under many generic forms like Lupin and Teva. If you’ve picked up a green antibiotic pill or capsule with 219 on it, you’re most likely using a generic form.

Some ask, “Is Keflex the same as cephalexin?” The answer is yes. All cephalexin 500 mg capsules work the same way, regardless of the branding or appearance.

Cephalexin 500 mg and Sinus Infection: Does It Work?

Does cephalexin treat sinus infections? It can. While other antibiotics may be preferred initially, cephalexin is an alternative for those with specific medical histories or allergies.

Patients may also ask, “Will cephalexin treat a sinus infection?” or “How long does cephalexin take to work?”—many start to feel better within 48 to 72 hours, but it’s essential to complete the full course.

Cephalexin 500 mg continues to be a trusted option for treating a wide range of bacterial infections—from UTIs and sinusitis to skin infections and beyond. When used appropriately, it delivers reliable results with a generally well-tolerated side effect profile. Always follow your doctor’s directions, and complete the full prescribed course to ensure proper healing and avoid antibiotic resistance.

Seeking Help Beyond the Prescription? Asana Recovery Is Here for You

If you’re relying on antibiotics like cephalexin 500 mg to manage recurring infections tied to substance use, it may be time to address the root cause. At Asana Recovery, we understand that physical health issues—such as urinary tract infections, skin abscesses, or respiratory infections—can be signs of a deeper struggle with addiction. Our compassionate team offers comprehensive, evidence-based care that treats both the body and the mind. Whether you’re dealing with UTIs, skin infections, or chronic illnesses related to substance use, we’re here to support your recovery journey. Don’t just treat the symptoms—take the first step toward lasting healing with Asana Recovery.

Frequently Asked Questions About Cephalexin 500 mg

What is cephalexin 500 mg used for?

Cephalexin 500 mg is a broad-spectrum antibiotic commonly prescribed to treat a wide variety of bacterial infections. It is frequently used for urinary tract infections (UTIs), sinus infections, skin infections, ear infections, and dental infections such as abscesses or toothaches. Many patients also receive cephalexin for strep throat and other respiratory tract infections. Branded under names like Keflex, Lupin 500, and Teva 3147, this antibiotic is known for its versatility and effectiveness.

Is cephalexin 500 mg a strong antibiotic?

Yes, cephalexin 500 mg is considered a strong antibiotic in the class of cephalosporins. It effectively targets gram-positive and some gram-negative bacteria, making it a first-line treatment for conditions like cephalexin for UTI, sinus infections, ear infections, and dental infections. It’s not the strongest antibiotic available, but for many common bacterial infections, it works quickly and reliably—often within 24–48 hours of the first dose.

How long does it take for cephalexin 500 mg to work?

Most people begin to feel relief from symptoms within 48 hours of taking cephalexin 500 mg, especially for infections like UTIs, sinus infections, or ear infections. However, it’s important to complete the full course—typically 500 mg taken 3 to 4 times a day for 7–10 days—to ensure the infection is fully eliminated and to avoid antibiotic resistance.

Can I take cephalexin 500 mg for a sinus infection?

Absolutely. Cephalexin 500 mg for sinus infection is a common prescription, especially when the infection is bacterial. Doctors may recommend Keflex 500 mg (the brand name) or its generic cephalexin 500 mg capsule. It targets the bacterial cause and helps relieve pressure, congestion, and inflammation in the sinuses.

Does cephalexin 500 mg treat urinary tract infections (UTIs)?

Yes, cephalexin 500 mg is highly effective for treating UTIs, especially in cases of uncomplicated lower urinary tract infections. The typical cephalexin 500mg dosage for UTI is 500 mg taken every 6 hours, although this may vary by case. If you’re prescribed cephalexin for UTI, it’s essential to complete the full course—even if symptoms subside quickly.

Can cephalexin 500 mg be used to treat a tooth infection?

Yes, cephalexin 500 mg is often used for dental infections such as abscessed teeth or gum infections. Patients may recognize this prescription as green capsule 219, Lupin 500, or Teva 3147—all of which are common identifiers of the cephalexin 500 mg capsule. It helps reduce pain and swelling while eradicating the underlying bacterial cause.

Is cephalexin the same as Keflex?

Yes, Keflex is the brand name for cephalexin. Whether you’re prescribed Keflex 500 mg or generic cephalexin 500 mg capsules, you’re receiving the same active ingredient. The difference lies only in branding and price, not effectiveness.

Does cephalexin contain sulfa or penicillin?

No, cephalexin is not a sulfa drug and does not contain penicillin. However, it is a cephalosporin antibiotic, which is related to penicillin. Some individuals allergic to penicillin may react to cephalexin, so it’s important to discuss allergies with your doctor before starting treatment.

What are the side effects of cephalexin 500 mg?

Common side effects of cephalexin 500 mg include upset stomach, diarrhea, nausea, dizziness, and headache. Some individuals report that the cephalexin green capsule 219 or the red Teva 3147 pill has a distinctive sulfur smell, which is normal but can be off-putting. In rare cases, it may cause allergic reactions, yeast infections, or rashes, so monitor your symptoms and speak to your doctor if concerns arise.

Can I take cephalexin 500 mg for an STD like chlamydia or gonorrhea?

While cephalexin may be prescribed for some bacterial STDs, it is not typically the first-line treatment for chlamydia or gonorrhea. However, in some off-label cases or penicillin allergies, doctors may prescribe cephalexin for STD treatment depending on bacterial sensitivity. Always consult your physician for STD-specific antibiotics.

Informational Sources

• Centers for Disease Control and Prevention. (2022). Antibiotic prescribing and use: Cephalexin. Retrieved from https://www.cdc.gov/antibiotic-use/community/for-patients/common-illnesses/cephalexin.html
  
  
• Mayo Clinic. (2023). Cephalexin (Oral Route). Retrieved from https://www.mayoclinic.org/drugs-supplements/cephalexin-oral-route/description/drg-20073315
  
  
• National Library of Medicine. (2023). Cephalexin. MedlinePlus. Retrieved from https://medlineplus.gov/druginfo/meds/a682733.html
  
  
• Drugs.com. (2024). Cephalexin 500 mg: Uses, dosage, and side effects. Retrieved from https://www.drugs.com/dosage/cephalexin.html
  
  
• U.S. National Library of Medicine. (2023). DailyMed: Cephalexin. Retrieved from https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=5f96e5a4-5cbe-4e45-8e06-74c117b9fc55
  
  
• American Dental Association. (2023). Antibiotics for dental infections. Retrieved from https://www.ada.org/resources/research/science-and-research-institute/oral-health-topics/antibiotics