A CT scan with contrast can provide valuable diagnostic information with minimal to no long term effects in most people. But it can cause few side effects like allergic reaction to the dye in some people and in people with underlying kidney diseases, diabetes and dehydration, can cause contrast induced acute kidney injury within 2448hrs of contrast exposure. In most cases, it resolves within a week. So adequate hydration is important when contrast dye is used.

The amount used is not too much but kid y function shd be checked before that

There are no significant long term effects of a CT scan with contrast.

The dyes used in connection with CT or MRI are harmless and are cleared from the body within at most a 24 hour period. The X-ary exposure in a CT is signifcatn, however, and impaired vision could result from 8+ CT scans of the head.