Any medicine be it Natural or Allopathic cannot be taken as reliable unless it has gone through Clinical Trials in a controlled environment on humans. 

All allopathic medicines undergo clinical trials to evaluate their effectiveness against a disease where as natural medicines including Homeopathy Ayurvedic etc have no such norms to be met before introduction into the market.

Thus the effectiveness of Natural Medicines is a highly debatable topic. Some  parts of Natural therapy aim at only boosting the existing immune system of a person. Which at times does prove to be helpful to the patient. But that process is a long drawn process it does not provide a quick-fix like allopathy.

Depending upon what your illness is you may opt for natural medicine if you are ready to bear the pain for a long time.