Oral supplementation has low efficiency, but taking higher doses can compensate.

There are some formulations that purport to have higher bioavailability on a gram-for-gram basis according to trials, but their price is often high enough that it’s cheaper to take more of a generic CoQ10 than to buy an expensive formulation.

CoQ10 supplementation has resulted in insomnia for some. I triggered it with higher doses (600-900mg per day) before I realized what was happening. Dropping down to 300mg alleviated the insomnia after about a week, which I interpreted as meaning the supplement was doing something.