Is too much ginger harmful

The short answer is yes.

The FDA has ginger on their "Generally Recognized As Safe" list. However, it can interact with certain medications such as blood thinners. Since ginger helps stimulate bile production, it is contraindicated in people who suffer from gallstones. An acute ginger overdose can cause intoxication by over-stimulating the central nervous system.

Some people may suffer allergic reactions to ginger in the form of rashes. Some people may suffer gas, belching, nausea, heartburn, and bloating, particularly if they take it in powdered form. Fresh ginger can cause intestinal blockage if it is not chewed properly, and those who have had ulcers, inflammatory bowel disease or blocked intestines should not consume large quantities of fresh ginger. It is also possible that that ginger may affect blood pressure, heart rhythms, and clotting.

In 2011, there was a recall and seizure of ginger products in Taiwan which were made from Hebo Natural Products Limited of China. Some of the ginger was contaminated with diisobutyl phthalate.