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Below are the general guidelines for dosing cephalexin. Note that these dosages may be adjusted on a case-by-case basis for individual patients. Always follow your prescribing physician’s instructions for taking cephalexin.

The following information comes from DailyMed, an FDA label information provider.

What if I miss a dose of cephalexin?

According to Mayo Clinic, if you miss a dose of cephalexin, take your missed dose as soon as possible, unless you are closer to your next dosing time. If the latter is the case, skip the missed dose and wait until the next one. Never double doses.

What if I overdose on cephalexin?

Signs and Symptoms — Symptoms of oral overdose may include nausea, vomiting, epigastric distress, diarrhea, and hematuria. If other symptoms are present, it is probably secondary to an underlying disease state, an allergic reaction, or toxicity due to ingestion of a second medication.

Treatment — To obtain up-to-date information about the treatment of overdose, a good resource is your certified Regional Poison Control Center. Telephone numbers of certified poison control centers are listed in the Physicians’ Desk Reference (PDR). In managing overdosage, consider the possibility of multiple drug overdoses, interaction among drugs, and unusual drug kinetics in your patient.

Unless 5 to 10 times the normal dose of cephalexin has been ingested, gastrointestinal decontamination should not be necessary.

Protect the patient’s airway and support ventilation and perfusion. Meticulously monitor and maintain, within acceptable limits, the patient’s vital signs, blood gases, serum electrolytes, etc. Absorption of drugs from the gastrointestinal tract may be decreased by giving activated charcoal, which, in many cases, is more effective than emesis or lavage; consider charcoal instead of or in addition to gastric emptying. Repeated doses of charcoal over time may hasten elimination of some drugs that have been absorbed. Safeguard the patient’s airway when employing gastric emptying or charcoal.

Forced diuresis, peritoneal dialysis, hemodialysis, or charcoal hemoperfusion have not been established as beneficial for an overdose of cephalexin; however, it would be extremely unlikely that one of these procedures would be indicated.

The oral median lethal dose of cephalexin in rats is 5,000 mg/kg.

Dosage and Administration

Cephalexin is administered orally.

Adults— The adult dosage ranges from 1 to 4 g daily in divided doses. The usual adult dose is 250 mg every 6 hours. For the following infections, a dosage of 500 mg may be administered every 12 hours: streptococcal pharyngitis, skin and skin structure infections, and uncomplicated cystitis in patients over 15 years of age. Cystitis therapy should be continued for 7 to 14 days. For more severe infections or those caused by less susceptible organisms, larger doses may be needed. If daily doses of cephalexin greater than 4 g are required, parenteral (IV)((intravenous)) cephalosporins, in appropriate doses, should be considered.

Pediatric Patients — The usual recommended daily dosage for pediatric patients is 25 to 50 mg/kg in divided doses. For streptococcal pharyngitis in patients over 1 year of age and for skin and skin structure infections, the total daily dose may be divided and administered every 12 hours. Examples for pediatric dosing is below: (tsp = teaspoon) (q.i.d. = 4 times a day) (b.i.d. = twice a day)

Cephalexin Suspension
Weight125 mg/5 mL
10 kg (22 lb)1/2 to 1 tsp q.i.d.
20 kg (44 lb)1 to 2 tsp q.i.d.
40 kg (88 lb)2 to 4 tsp q.i.d.
Weight250 mg/5 mL
10 kg (22 lb)1/4 to 1/2 tsp q.i.d.
20 kg (44 lb)1/2 to 1 tsp q.i.d.
40 kg (88 lb)1 to 2 tsp q.i.d.
or
Weight125 mg/5 mL
10 kg (22 lb)1 to 2 tsp q.i.d.
20 kg (44 lb)2 to 4 tsp q.i.d.
40 kg (88 lb)4 to 8 tsp q.i.d.
Weight250 mg/5 mL
10 kg (22 lb)1/2 to 1 tsp b.i.d.
20 kg (44 lb)1 to 2 tsp b.i.d.
40 kg (88 lb)2 to 4 tsp b.i.d.

In severe infections, the dosage may be doubled.

In the therapy of otitis media, clinical studies have shown that a dosage of 75 to 100 mg/kg/day in 4 divided doses is required.

In the treatment of β-hemolytic streptococcal infections, a therapeutic dosage of cephalexin should be administered for at least 10 days.

How is cephalexin supplied?

Cephalexin For Oral Suspension, USP is available in:

The 125 mg per 5 mL oral suspension* is pink in color with a strawberry flavor and is available as follows:

100 mL Bottles NDC 63304-958-01

200 mL Bottles NDC 63304-958-02

The 250 mg per 5 mL oral suspension* is pink in color with a strawberry flavor and is available as follows:

100 mL Bottles NDC 63304-959-01

200 mL Bottles NDC 63304-959-02

* After mixing, store in a refrigerator. May be kept for 14 days without significant loss of potency. Shake well before using. Keep tightly closed.

Cephalexin Capsules, USP are available in:

250 mg dark green and white, size 2, printed “RX656” on both cap and body.

(28s) NDC 63304-656-27

(100s) NDC 63304-656-01

(500s) NDC 63304-656-05

500 mg, dark green and light green, size 0, printed “RX657” on both cap and body.

(28s) NDC 63304-657-27

(100s) NDC 63304-657-01

(500s) NDC 63304-657-05

The bottle packages contain desiccant.

Dispense in tight, light-resistant container.

Store at 20 – 25° C (68 – 77° F). (See USP Controlled Room Temperature).

Disclaimer: this article does not constitute or replace medical advice. If you have an emergency or a serious medical question, please contact a medical professional or call 911 immediately. To see our full medical disclaimer, visit our Terms of Use page.


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