Bactrim Dosing For A UTI In A 6 Year Old Child
In our latest question and answer, the pharmacist discusses the dosing of Bactrim Suspension to treat a UTI in a 6 year old child.
Can you tell me the normal pediatric Bactrim suspension dose for a 60-pound female being treated for a urinary tract infection? She is 6 1/2 years old.
Jul 11, 2022- Bactrim is a combination antibiotic containing sulfamethoxazole and trimethoprim that works together to treat urinary tract infections.
- For children ages 3 to 17 with a UTI, the typical dose is based on the child's weight and given in two divided doses throughout the day.
- A doctor will determine the exact dose needed for your child and may round the calculated amount to an easier-to-measure dose like teaspoonfuls.
Hello and thanks for your question! We are more than happy to answer this for you.
To start off, it is important to know that Bactrim is a combination drug product, containing both sulfamethoxazole and trimethoprim. They work synergistically as antibiotics.
Bactrim Suspension (also known as Septra) is available in a concentration of sulfamethoxazole/trimethoprim 200mg-40mg/5mL (i.e. 200mg sulfamethoxazole and 40mg trimethoprim per 5mL).
Bactrim UTI Dosage For Children 3-17
The recommended dosage to treat a UTI (urinary tract infection) in children and adolescents aged 3 to 17 years is:
- Per the Prescribing Information For Bactrim: 8mg/kg per day (trimethoprim component) given in two divided doses
- Per the American Academy of Pediatrics: 6-12 mg/kg per day (trimethoprim component) given in two divided doses
So, let's find the dosage for the example you give, a 60-pound female that is 6 and 1/2 years old. We'll use 8mg/kg per day:
- 60 pounds converts to 27.21 kilograms (60 pounds/2.205).
- 8mg (times) 27.21 kilograms equals 217.68 mg trimethoprim per day.
- Bactrim suspension is available in a concentration of 200mg-40mg/5mL.
- Converting 217.68mg trimethoprim per day into a volume (based on 200mg-40mg/5mL) equals 27.21 mL per day.
- Since Bactrim is dosed twice daily, this comes out to ~13.6mL two times daily
One teaspoonful is equivalent to 5mL, so I imagine the doctor in this situation would prescribe either exactly 13.6mL twice daily or 3 teaspoonfuls (15mL) twice daily to ease with measuring.
Final Words
Thanks again for your question and please feel free to reach out again if anything else comes up!
References & sources
- Bactrim Suspension — AccessFDA
- Urinary Tract Infection: Clinical Practice Guideline for the Diagnosis and Management of the Initial UTI in Febrile Infants and Children 2 to 24 Months — American Academy of Pediatrics
- Urinary Tract Infections in Children — American Academy of Pediatrics
Glossary — Terms in This Answer
- Bactrim
- A prescription antibiotic medication that combines two drugs to treat bacterial infections.
- Sulfamethoxazole
- An antibiotic drug that is one of the two active ingredients in Bactrim.
- Trimethoprim
- An antibiotic drug that is the second active ingredient in Bactrim.
- Synergistically
- When two drugs work together to produce a stronger effect than either could produce alone.
- Suspension
- A liquid medication form where solid particles are mixed throughout a liquid so it can be swallowed easily.
- Concentration
- The amount of active medication contained in a specific volume of liquid.
- Mg/kg
- A measurement of medication dose expressed as milligrams of drug per kilogram of body weight.
- UTI
- A urinary tract infection, which is a bacterial infection of the bladder, urethra, or other parts of the urinary system.
Dr. Brian Staiger, PharmD
Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified
Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...
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