Short answer
There is no weight-based dosing chart for pediatric medical cannabis in general. The only cannabinoid medicine with FDA-approved pediatric weight-based dosing is prescription cannabidiol oral solution, which is labeled at 2.5 mg/kg twice daily (5 mg/kg/day) to start, titrated to 5 mg/kg twice daily (10 mg/kg/day) and capped at 10 mg/kg twice daily (20 mg/kg/day) under a neurologist's supervision. For any other product, including dispensary tinctures, gummies, and THC-dominant oils, no pediatric mg/kg standard exists. The dose is a clinical decision made by a qualified prescriber, and major pediatric bodies advise against use outside approved indications.
cannabis oil dosage for child safety
What follows is how weight enters the calculation, and how caregivers support that calculation safely.
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Prerequisites
- A prescriber who is actively managing the child and has set a dose in mg/kg
- The child's current weight in kilograms, taken the same day
- Product labeling that states concentration in mg/mL, plus a batch certificate of analysis
- An oral syringe marked in 0.1 mL increments
- A written dose log with time, amount, symptoms, and side effects
How the weight-based calculation works
- Confirm the prescriber has given you a dose in milligrams per kilogram of body weight, not a fixed milligram amount.
- Weigh the child in kilograms on the same scale each time, and write the number down.
- Read the product label and record the concentration in mg/mL.
- Multiply the child's weight in kg by the prescribed mg/kg to get the milligrams for one dose.
- Divide that milligram figure by the concentration in mg/mL to get the volume in mL for one dose.
- Draw that volume with the oral syringe, never with a kitchen spoon or a dropper from another bottle.
- Give the dose at the interval the prescriber set, and hold all increases until the prescriber authorizes the next titration step.
- Record the dose, the time, and any change in symptoms or behavior in the log.
- Re-weigh the child and recalculate whenever weight changes, because a dose that fit last month may not fit this month.
- Call the prescriber before making any change on your own, including skipping, doubling, or combining with another product.
Worked example
A 20 kg child prescribed 2.5 mg/kg per dose needs 50 mg per dose. If the bottle is 100 mg/mL, that is 0.5 mL. The same child at 22 kg needs 55 mg, or 0.55 mL. Small weight changes move the volume, which is why the scale reading matters more than the mark on the syringe.
Stop and call the prescriber for these signs
- Unusual sleepiness, limpness, or trouble waking
- Rash, hives, or facial swelling
- Vomiting, poor appetite, or weight loss
- Yellowing of eyes or skin, or dark urine
- Any new medication, supplement, or herbal product added to the child's routine
Why most pediatric cannabis has no weight-based dose
Pediatric pharmacokinetic data for THC-dominant products are thin, product potency varies between batches, and children metabolize cannabinoids differently than adults. Unregulated products may contain contaminants, inaccurate potency, or synthetic cannabinoids. Labs can also shift over time on the same dose as liver enzymes rise, which is why blood work is part of monitored therapy. Convenience products sold for adults, including gummies and vape cartridges, are not built around mg/kg accuracy and should not be converted into a pediatric dose at home. If a clinician has not set the number, there is no safe number to calculate.