Boots ketoconazole shampo(and possibly Nizoral) side effects

[vauxall]

I've just bought the Boots ketoconazole shampoo (a cheap Nizoral clone) and I see this on the instructions:

"After you use this medicine:

[...]

- An increase in normal hair loss
- Discoloration of your hair if you have [...] grey hair.

Should I worry?

 

[casperz]

I've got some grey hair and nizoral never affected it.