Driving with a missing lug nut can put extra stress on the remaining lug nuts and the wheel itself. While it might not cause immediate harm, it's not advisable to drive long distances or at high speeds with a missing lug nut. The wheel's balance and integrity could be compromised, leading to uneven wear or, in extreme cases, the wheel coming off. If you notice a missing lug nut, it's best to replace it as soon as possible.