Brief Answer:
Nausea, gastric irritation, mucositis, teach your kid to spit the foam

Detailed Answer:
Thanks for your query. I have gone through your query.
As far as the swallowing foam of tooth paste by your kid is concerned, it might result in adverse effects like gastric irritation, mucositis, and nausea. If these adverse effectd results, it will be severe in children since they are too young to with stand these effects. So it is better to teach your kid to spit the tooth paste foam after brushing. You can make him rinse his mouth with saline and train him to spit, then your kid will brush and spit. If your kid swallow the foam once or twice nothing will happen but on regular basis it result in above said complications. There is no other alternative to avoid this than training your kid.
I hope I have answered your query. if you have any queries reply me back. take care.

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