Black henna can contain many things except henna. It is likely to contain indigo or other more permanent dyes and it's not safe, it can cause allergic reactions in many cases. Normal henna leaves a brownish color. I'm not sure where you are or what your means are but home hair dyes are a much better alternative.
Prior to the availability of the pure levothyroxine, desiccated animal thyroid extract was the only treatment for hypothyroidism. Today, some individuals prefer dessicated thyroid extract as a more natural thyroid hormone.
Levothyroxine (Synthroid, Levoxyl, Levothroid, Unithroid, Tirosint, Levo-T) is a synthetic version of the principle thyroid hormone, thyroxine (T4), which is made and released by the thyroid gland. Thyroid hormone increases the metabolic rate of cells of all tissues in the body. It is prescribed to treat hypothyroidism and to suppress thyroid hormone release in the management of cancerous thyroid nodules and growth of goiters. It is important to be aware of drug interactions, as well as common side effects on the user.