If they don't, then you need to take a HARD look at your diet. You need to get an in depth blood work test done to see what vitamins, etc are deficient in your body.
For example, if you are low on Iodine or D3, that could inhibit your body's ability to properly receive herbal remedies.
There is a reason why "folklore and old wives tales" exist…. because they work. Ignorance of how the human body works is not excuse.