I got a positive lh test this morning, is it too late to take a plan b pill for it to be effective?

?LH? The effectiveness of emergency contraception depends on the type used. Most give the time frame of 3 days and one lists 5. If you are pregnant it does not.

The LH test indicates ovulation has occurred or is imminent, so in the latter case Plan B could still be effective since it works by delaying ovulation. However, the chance it will not work is certainly higher. Plan B is better than nothing but has a high failure rate under the best of circumstances. Talk to your doctor about your options for more effective birth control.