Are all herbal remedies safe?

No. Are all medicines safe? Remember that nightshade is a herb, so too is oleander both are very poisonous.
Keep in mind. Keep in mind that medicinal herbs are a form of medicine and like synthetic meds have side effects, drug interactions and toxicities. Check with your doc if you're on meds. Definitely stop any herb if you have wheezing, shortness of breath, itching, hive or angioedema.
Some yes, some no. There are many herbal remedies, with varying characteristics, safety, & effectiveness. A good general resource for you is national center for complementary & alternative medicine: http://nccam.Nih.Gov/health/herbsataglance.Htm for integrative medicine physicians who can work with you personally on this: www.Azcim.Org or www.Holisticboard.Org; naturopathic docs: www.Naturopathic.Org.
Caveaet emptor. "herbal remedies" imported from overseas, especially asia, are often not what they are supposed to be. They are unregulated and you assume the risk.
Herbal Products. A lot of herbal products have not been tested for safety so you have to do some research of your own because a lot of docs are not up on herbs.