Mistletoe

My doctor (he is a naturopath) is prescribing mistletoe for me to take for my arthritis. I would be taking injections 3x a week. He told me it is to get my immune system back up to par. I have been looking for information on mistletoe but have not been successful. Could you please tell me more about it & if you have ever heard of it being used for this before. Are there any dangers/side effects etc. I would very much appreciate it. I have not ordered it yet (I have to get it from a pharmacy in California). I don't want to order it until I find out more.

The young leaves and twigs of Mistletoe (Viscum album) are used as a relaxing nerve tonic and to lower blood pressure, especially in arteriosclerosis. It stimulates the vagus nerve, resulting in a slowing of pulse. Mistletoe's effect on the heart (slowing it) indicates that it be used only on prescription by a medical practitioner.
The berries are a potent medicine, to be used only on prescription by a medical practitioner. The berries may be used as an immune-enhancer. Historically, the berries have been used internally and externally for cancer tumours.
The Commission E Monographs, the German Therapeutic Guide for Herbal Medicines, notes that there have been cases of poisoning in children eating the berries. Mistletoe berries, leaves and twigs are listed in this guide as having no documented effectiveness for the claimed uses, and this guide does not recommend the use of mistletoe.
Thomas Bartram, in "Bartram's Encyclopedia of Herbal Medicine" (available at Richters), states that Mistletoe contains alkaloids, glycoproteins, polypeptides and flavonoids. Bartram lists its actions as tranquilizer, vasodilator, diuretic, immune enhancer and anti-inflammatory and notes that it has been used in arterial hypertension, insomnia, temporal arteritis, nervous excitability, hyperactivity, limb twitching, epilepsy (petit mal), chorea, tinnitus, withdrawal from benzodiazepine addiction, arteriosclerosis, headache, dizziness and fatigue.