Terbinafine pediatric dose calculator
Use this Terbinafine pediatric dose calculator to match the prescribed child dose to the exact liquid, tablet, or capsule strength before you give it.
dose calculator basics
Terbinafine pediatric dose calculator details
Use this Terbinafine calculator as the fast parent page for weight-based dose checks, mL conversion, common strengths, and the practical safety steps that generic calculator sites often skip.
Formula
mL per dose = (child weight in kg x prescribed mg/kg/day / doses per day) / medication concentration in mg per mL.
Worked example
For a 20 kg child using 6.25 mg/kg/day divided 1 time daily with 25 mg/1 mL, calculate the daily mg target, divide by the schedule, then convert that mg amount into mL for the selected product.
Safety checks before using the result
- Use the exact product strength in hand before measuring the dose.
- Confirm maximum dose, age limits, and indication-specific cautions when they apply.
- Escalate urgent symptoms or medication reactions instead of repeating doses from calculator output alone.
Practical dosing guide
Before you measure the dose
Use this page to match the prescribed Terbinafine plan to the exact liquid or tablet strength before the first dose.
- What it is usually used for
- Systemic allylamine antifungal used once daily for tinea capitis, onychomycosis, and other dermatophyte infections in children.
- Common forms
- Common forms include 250 mg tablet, 125 mg tablet (non-US), and 125 mg granules (discontinued in US).
- How the schedule is usually written
- Many outpatient plans are given once daily.
Terbinafine pediatric medication summary
Systemic allylamine antifungal used once daily for tinea capitis, onychomycosis, and other dermatophyte infections in children.
First-line systemic therapy for tinea capitis in many U.S. guidelines because of high mycologic cure rates and shorter courses than griseofulvin.
Weight-based once-daily dosing improves adherence compared with multi-dose regimens; counsel families about the full 6-week duration.
Terbinafine indications and common pediatric uses
Terbinafine is a core systemic option for pediatric dermatophyte disease when depth or location limits topical-only success.
Tinea capitis (especially Trichophyton species)
Tinea capitis (especially Trichophyton species): Hair regrowth can lag clinical cure.
Onychomycosis (selected pediatric/adolescent cases)
Onychomycosis (selected pediatric/adolescent cases): Appearance normalization may continue after treatment ends.
Extensive tinea corporis/cruris refractory to topical therapy
Extensive tinea corporis/cruris refractory to topical therapy: Escalate to dermatology if no response.
Refractory dermatophyte infection requiring alternate systemic strategy
Refractory dermatophyte infection requiring alternate systemic strategy: Avoid indefinite empiric continuation without measurable benefit.
How to give Terbinafine
- For terbinafine, execution quality matters: correct weight band, daily adherence, and early recognition of liver-warning symptoms.
- Two different weight-band schemes exist; use the one on the prescription and do not mix them. US granule label (FDA, tinea capitis, 4 years and older): under 25 kg 125 mg, 25-35 kg 187.5 mg, over 35 kg 250 mg once daily for 6 weeks. UK/AAFP tablet bands: 10-20 kg 62.5 mg, 20-40 kg 125 mg, over 40 kg 250 mg once daily. US granules are discontinued, so most children take part of a 250 mg tablet.
- Anchor dosing to a stable routine, track each dose on one caregiver log, and combine with scalp decolonization steps for tinea capitis.
Terbinafine side effects, contraindications, and interactions
Most children tolerate terbinafine well. Side-effect safety depends on early recognition of uncommon but serious hepatic or severe skin reactions.
Common side effects
- Counsel every family on liver-warning symptoms before first dose.
- Treat persistent taste/smell changes as clinically meaningful in children with intake decline.
- Escalate severe rash, jaundice, dark urine, or systemic illness immediately.
Safety checks
- Liver disease: Terbinafine metabolism is hepatic and serious liver injury is rare but documented.
- Severe renal impairment: Metabolite handling may be altered.
- Hepatic warning symptoms: Rare but serious liver injury risk.
- Severe skin/mucosal reaction: Potential severe cutaneous adverse reaction.
Drug interactions
- Review the full medication list with a clinician or pharmacist before combining therapies.
Terbinafine mechanism and clinical pearls
Terbinafine inhibits fungal squalene epoxidase, reducing ergosterol synthesis and causing intracellular squalene accumulation that damages fungal cell membranes.
Adopt once-weekly telehealth check-ins during the first 3 weeks to reinforce adherence and side-effect screening.
Frequently asked questions about Terbinafine
Most courses last 6 weeks. Some dermatologists extend to 8 weeks if there is slow clinical response or if Microsporum species are suspected.
The label recommends checking liver enzymes before starting terbinafine in every patient. Call immediately for symptoms of liver injury such as jaundice or dark urine.
Tablets are scored and may be split or crushed and mixed with soft food to help younger children swallow, but ensure the full dose is taken and rinse the mouth afterward.
Sources reviewed for Terbinafine
cdc-ringworm-2024
statpearls-tinea-capitis-2024
dailymed-terbinafine-2024
statpearls-onychomycosis-2024
statpearls-terbinafine-2025
Ringworm Treatment
Centers for Disease Control and Prevention
Source