Another example would be when the person providing their own care or seeking their own care is not aware of potential interactions with other products they're taking. They can be pharmaceutical or other NHPs. They're also not well aware of contraindications. If they have liver, heart, kidney or eye disease, maybe this is not the right product for them and they don't know it. Those, then, are preventable harms. Had they known, they wouldn't have used that NHP.
Then there are the warnings, and not having clear warnings on the package or having difficulty finding them until they get home or until after they've taken the medication. Had they known about that warning, they actually wouldn't have used this product, or they would have chosen a different product for their care or their family's care.