Some facts about Herbal medicine

Herbal medicines are often used by Africans but does it really works?
 These are some facts about herbal drugs
1. Herbal medicines doesn't have dosage,it doesn't matter any dosage taken
2. No scientific explanations on how herbal medicine cure the stipulated disease
3. Materials used in formulating herbal medicine are things you don't expect can cure an ailment.
4. Herbal treatment cure some disease conventional medicine can't cure
5. Herbal drugs are often more expensive