What is a key characteristic of OTC products that contain ephedrine?

The key characteristic of over-the-counter (OTC) products that contain ephedrine is that they are required to be clearly labeled with their active ingredients. This regulation is in place to ensure consumer safety and transparency, allowing individuals to make informed decisions about the medications they are purchasing. Clear labeling helps to prevent accidental overdose and enables consumers to be aware of the presence of ephedrine, known for its stimulant properties, so they can use these products appropriately and in accordance with any existing health conditions or medication regimens.

In contrast, some of the other options suggest misconceptions about OTC ephedrine products. The notion that these products must only be available through special pharmacies is not accurate; while there might be restrictions on the sale of ephedrine due to its potential for misuse, they are not confined to specific pharmacies. Additionally, while it is true that these products can contain stimulants, the option stating they cannot contain any stimulants is incorrect, as ephedrine itself functions as a stimulant. Finally, referencing high levels of ephedrine is misleading as the regulations focus on proper labeling regardless of the quantity of the ingredient.