The amount of lactose in the tablet would be minuscule. I'm lactose intolerant...which doesn't mean an allergy, it just means you lack an enzyme to break down lactose. I try to avoid dairy but it isn't always possible as it's in many foods, cakes, biscuits etc. It's usually tolerated like that with other foods but a glass if milk would have me in the loo in a short time.
Anyhow, if you are worried, you can buy lacteeze tablets from a pharmacy which has the enzyme in it. I use them a lot when eating out as you never know everything that's in what you order.