Carl's Jr. is adding something special to its signature sauce.

The restaurant will test a CBD-infused burger at one of its Denver locations for one day only: April 20, the unofficial holiday for cannabis enthusiasts.

The limited-time offer makes Carl's Jr. the first national fast food chain to add CBD-infused food to its menu. In another nod to the marijuana holiday, the burger will sell for $4.20.

The burger chain's Rocky Mountain High: CheeseBurger Delight features two beef patties, pickled jalapenos, pepper jack cheese, waffle fries — and about 5 milligrams of hemp-derived CBD extract in the burger chain's Santa Fe Sauce.

Proponents claim that CBD, a non-psychoactive compound found in hemp and marijuana, can help with anxiety and pain relief, among other ailments, although little scientific research has been done to back up those assertions.

There is also a lack of agreement about dosage, particularly when CBD is added to food. Compared to its close cousin marijuana, hemp contains less THC, the psychoactive chemical in cannabis. So Carl's Jr.'s burger is unlikely to get you high.