Depends on the vitamin. It's difficult to overdose on Vitamin C for example. Vitamin D should be dosed with caution, but taking e. g. 1000 IU a day should be safe even if you get it from other sources.

That's true, but you have to do some really silly things to get to that point. You're not going to overdose on a multivitamin from the supermarket.

overdosing on Vitamin D is not really a thing

Hypercalcæmia?

Actually, it is possible to overdose on vitamin D, though it’s relatively rare. Vitamin D toxicity, also known as hypervitaminosis D, occurs when there is an excessive amount of vitamin D in the body. This can happen through very high doses of supplements over an extended period or by accidental ingestion of high-dose vitamin D supplements.

everything including water can be toxic at high doses. when I say its not really a thing, it means that it is indeed very uncommon compared to the amount of people who take supplements.

Ok, so paracetamol (aka Tylenol, acetaminophen) overdose is also 'not really a thing', because despite it being absolutely possible to trash your liver and die, the number of people who do that (including as a suicide attempt, as does happen) is miniscule compared to the approximately everybody who takes it.

The safety margin for Vitamin D is on a totally different scale vs the safety margin of Paracetamol (which is very thin, it's easy to overdose on it). bad analogies are bad.

Unfortunately, this is quite common among parents who want to make their own infant formula. They don't know how to dose milligrams and give ten or a hundred times the prescribed dose to infants.

https://www.anses.fr/en/content/vitamin-d-opt-medicines-avoi...

The blood test for vitamin D my doctor showed me includes a safe range.