Balancing chemical equations is a key chemistry skill. Use these step by step instructions to write and balance chemical equations. Balancing chemical equations is a key chemistry skill. Use these step by step instructions to write and balance chemical equations.
So, there are many signs and symptoms of Selenium Overdose- some occur very early and some occur much later. 1  Early Signs: Some of the early signs of Selenium Toxicity are endocrine hormone disturbances- particularly thyroid issues. Poor hair and nail growth are early signs that are probably the easiest to notice.
Symptoms of an Overdose. As you might expect, a senna overdose is likely to cause a strong laxative effect. In particular, diarrhea, cramping, bloating, and abdominal pain may be expected. Other than those problems, it is not clear if senna might cause other, more serious problems.