A white blister under the tongue of a child is mainly caused by the following two conditions. The first is caused by children suffering from tongue inflammation, if the children after cold or fatigue, the immunity will be reduced in this case the pathogenic bacteria will take advantage of the situation, which will lead to the children to appear inflammation. If the inflammation mainly occurs in the children’s tongue, it will cause the appearance of white blisters under the tongue, for this situation need to be anti-inflammatory, pain treatment. For example, you can apply the open-throat sword spray or tin powder, watermelon cream and so on, these drugs have good pain relief and anti-inflammatory effect. Secondly, it is due to the children’s micronutrient deficiencies, if there are micronutrient zinc deficiencies or vitamin B deficiencies, this situation will cause mouth ulcers. If the mouth ulcers are recurrent and mainly under the tongue, they can also cause white blisters on the underside of the tongue. Zinc and vitamin B supplements can be given to children in this situation.