Estimated reading time: 8 minutes
Medication Overview for Cephalexin
Cephalexin, known by its brand name Keflex, is an antibiotic medication belonging to the cephalosporin class of antibiotics. It kills bacteria, supporting its use in treating bacterial infections, particularly those in the respiratory tract, lungs, skin, bones, urinary tract, genitals, and ears. It is indicated for individuals older than one year of age, providing safe and effective treatment for several different conditions.
Medical Indications for Cephalexin
Cephalexin can treat certain types of bacteria in various infections, including the following:
- Respiratory tract infections
- Bone infections
- Ear infections
- Genitourinary tract infections
- Skin infections
Prolonged and continued exposure to antibiotics runs the risk of developing drug-resistant bacteria. Developing drug-resistant bacteria makes antibiotics less effective in treating your current and future infections. Thus, to support cephalexin and other antibiotics’ efficacy, cephalexin should only be used when clinically indicated for certain types of bacteria.
This can be validated using susceptibility information, or if this is not available, using local epidemiology and susceptibility patterns and data to allow for empiric therapy selection. Your doctor will select an antibiotic for you based on this information. Cephalexin can treat the following bacteria:
- Streptococcus pneumoniae
- Moraxella catarrhalis
- Staphylococcus aureus
- Klebsiella pneumoniae
- Proteus mirabilis
- Haemophilus influenzae
- Streptococcus pyogenes
- Escherichia coli
Dosage and Administration
Your dose of this medication and the duration of therapy will depend on your diagnosis, age, and weight (for pediatrics). Usually, cephalexin is given for seven to 14 days, depending on the type of infection and its severity.
It is available in tablets, capsules, and a liquid formulation. Each of these formulations has a similar dosing.
Typical dosing is as follows:
- For adults and pediatrics >15 years old
- 250 mg every six hours
- Alternatively, 500 mg every 12 hours
- Pediatrics ages 1 to <15 years of age
- Ear infections: 75 to 100 mg/kg total daily dose administered in equally divided doses every six hours
Dose Adjustments
Dose adjustments are required for patients with severe and end-stage renal disease (ESRD). This condition is when you have a creatinine clearance of less than 30 mL/min.
Additionally, if you use the oral suspension formulation, you must mix the liquid. You can find mixing directions on the label. Always shake the bottle well before administering.
The dosing above is the usual dosing. However, you should always discuss with your doctor how to take your medication and take it exactly as directed. Never take more or less than what has been prescribed.
Potential Side Effects of Cephalexin
Cephalexin is known to cause a few side effects, most of which are mild and temporary. The most common ones include gastrointestinal (GI) related issues, including nausea, vomiting, diarrhea, indigestion, and stomach pain. However, others have been reported, including:
- Inflamed stomach lining
- Vaginal discharge
- Redness
- Arthritis/joint pain
- Vaginitis
- Neutropenia
- Eosinophilia
- Thrombocytopenia
- Candidiasis
If you experience any side effects with cephalexin that you find concerning, contact your doctor. You may need to be switched to another antibiotic.
Precautions and Contraindications
There are a few adverse events that can happen when taking cephalexin. These include:
- Severe allergic reactions. Signs of allergies include rash, itchiness, swelling, redness, and anaphylaxis. Other severe allergic reactions have been reported, including toxic epidermal necrolysis and Stevens-Johnson syndrome. It is important to consider other antibiotic allergies when starting cephalexin or any antibiotic. Ten percent of individuals with penicillin are also allergic to beta-lactam antibacterials, including cephalexin.
- Clostridium difficile (C. diff) and diarrhea. C. diff is a type of bacteria that causes inflammation in the colon and consequent diarrhea. It is a serious infection that is more likely to occur if you are on antibiotics or have taken antibiotics recently. It causes uncomfortable symptoms such as diarrhea, stomach pain, nausea, fever, and loss of appetite. It is contagious, and there is a high likelihood of re-infection even after it resolves.
- Drug resistance. Use of cephalexin for extended periods can cause drug-resistant bacteria to develop. This can make antibiotics less effective on your current and future infections. Thus, you should only take cephalexin if necessary and for the right kind of bacteria.
- Prolonged prothrombin time. Prothrombin time is how long it takes your blood to clot. Cephalexin can make this time longer, meaning extra caution must be taken if you are on blood thinners or have certain conditions.
- Seizure. Seizures have occurred in individuals with kidney problems who have subsequently taken cephalosporin antibiotics. Cephalexin should be stopped if seizures happen, and anticonvulsant therapy should be given if required.
Interactions
Cephalexin may interact with other medications, having a negative impact on their efficacy or safety. To avoid drug interactions, always provide your doctor with your list of medications.
In particular, administering cephalexin with metformin (a diabetes drug), can increase metformin levels in the body. Taking both together would require additional monitoring. Additionally, the medication probenecid interacts with cephalexin, increasing its levels in the body.
Effectiveness and Expectations for Cephalexin
The effectiveness of cephalexin will depend on what you are using it for. However, several studies have been done in different types of infections and with different types of bacteria to characterize the safety and efficacy of cephalexin.
One such study evaluated individuals with pyogenic vertebral osteomyelitis (PVO) due to the methicillin-susceptible Staphylococcus aureus (MSSA). Findings indicated that cephalexin demonstrated a treatment success rate of 87 percent, making it very effective in treating this condition. Other research indicates cephalexin’s cure rates of 90 percent or more for streptococcal and staphylococcal skin infections.
Long-Term Use and Monitoring
Prolonged antibiotic treatment, including cephalexin, is not recommended unless clinically indicated. This is due to the risk of developing drug-resistant bacteria, which causes excessive antibiotic use.
Thus, you should only take cephalexin when a doctor recommends it for the exact duration that you are prescribed (no more and no less). In terms of monitoring, you will want to observe for resolving your infection symptoms. However, even if your symptoms improve or resolve completely, ensure you finish your entire course of antibiotics.
If you have kidney problems, your doctor will likely monitor your kidney function, given some of the risks. Additional monitoring will also need to be done for individuals on metformin or blood thinners.
Alternatives and Complementary Therapies
There may be situations where you want to switch your therapy from cephalexin to another drug. For example, you may experience side effects with cephalexin and want to switch. Several other antibiotics work similarly to cephalexin and will have comparable efficacy. These include:
- Amoxicillin (Amoxil)
- Amoxicillin clavulanate (Augmentin)
- Ciprofloxacin (Cipro)
- Sulfamethoxazole/trimethoprim (Bactrim)
- Levofloxacin (Levofloxacin)
- Azithromycin (Zithromax)
There are even more options than what is listed above. Therefore, if you have questions about switching your cephalexin to another medication, discuss it with your doctor.
Frequently Asked Questions (FAQs) About Cephalexin
Can you drink while on cephalexin?
Healthcare providers recommend avoiding drinking while on antibiotics such as cephalexin. However, If you choose to drink, do not do so heavily. Drinking can affect your ability to heal from an infection. It can also worsen the side effects of cephalexin, such as nausea.
How long does it take cephalexin to work?
Cephalexin can start working almost immediately within a few hours of taking it. However, it may take a few days to start seeing the resolution of your symptoms (roughly 48 hours).
Do I have to finish the prescription even if I feel better?
You should always finish the full course of antibiotics you are prescribed, even if you feel better. Even if your symptoms have subsided, you may still have bacteria. If you stop too early, you can develop what is known as “antibiotic resistance.” This occurs when the bacteria in your body changes so that it is resistant to the medication. That medication will no longer work for that bacteria and may not work again. Thus, finishing your whole course of cephalexin is very important.
Can cephalexin work for the cold and flu?
Cephalexin prevents the growth of bacteria, meaning that it does not fight against viral infections. The common cold and flu are considered viral infections and thus cannot be treated with antibiotics like cephalexin.
How do I store the cephalexin?
If you or your child are taking the cephalexin oral suspension, make sure to keep it refrigerated. Additionally, shake it well before using. If you are taking the tablets or capsules, keep them in a trying place at room temperature. Do not keep them in the bathroom.
How long will cephalexin stay in my body?
Your body will excrete over 90 percent of cephalexin within the first eight hours of your dose. However, this may take a bit longer if you have impaired kidneys.
Do I need to take cephalexin with food?
You can take cephalexin with or without food.
Visit PatientsLikeMe.com to explore thousands of treatment reviews. Tap into the shared knowledge of our community and see what has worked for other members. See how your experience aligns with the community and if another treatment can help, and trend data to understand what to expect when starting a new treatment.
Resources
- https://medlineplus.gov/druginfo/meds/a682733.html
- https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/050405s107lbl.pdf
- https://khealth.com/learn/medication/cephalexin/
- https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/050406s013lbl.pdf
- https://www.cdc.gov/cdiff/what-is.html#:~:text=C.%20diff%20(also%20known%20as,the%20United%20States%20each%20year.
- https://www.ncbi.nlm.nih.gov/books/NBK549780/#:~:text=Cephalexin%20is%20commonly%20utilized%20in,S%20aureus%20or%20Streptococcus%20pyogenes.
- https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-023-08266-0#:~:text=At%20the%20end%20of%20cephalexin%20treatment%2C%20the%20treatment%20response%20score,treatment%20success%20rate%20of%2087%25.
- https://pubmed.ncbi.nlm.nih.gov/6364089/