It's hard to think of a better example of prevention beating cure than sunburn and sunstroke, but accidents happen and so the advice below might be useful.
The symptoms of sunstroke are as follows: high fever, fast pulse, red hot skin but an inability to sweat, headache and nausea.
There are three homeopathic remedies described here which could well apply to your child's situation. Give the one which most closely resembles your child's symptoms in a 30c hourly for up to 6 doses. As the symptoms reduce in intensity, reduce the dosage similarly.
Sol
This remedy is prepared from potentised sunlight and can be very useful in managing many ill effects of the sun: not only sunburn and sunstroke but also prickly heat and sun headaches. If your child is very fair skinned, or if they are prone to finding strong sun difficult to manage, and you are heading for a sunny holiday, give them a single dose twice daily for the first 3 days of your holiday to enable your child to adjust more comfortably.
Belladona
This is an indispensable kids' remedy full stop. Give your child Belladonna if they produce a high fever, have red hot skin and perhaps appear delirious. Their pupils are liable to be dilated.
Apis
This remedy is produced from the honey bee, and is applicable when the skin is red, swollen and puffy. Your child will complain that their skin feels like it's burning or stinging.
In addition to these homeopathic remedies, do make sure your child is well hydrated, and seek medical help if symptoms worsen.
Many thanks for reading and don't hesitate to get in touch for further information.