Symptoms of an overactive thyroid gland are generally symptoms of an increased metabolism. These can include weight loss, nervousness or anxiety, irritability, a racing heart, increased bowel movements, sweating, sleeplessness, hand tremors, and muscle weakness.1  Previous.2  Continue.n addition to fatigue and weight gain, symptoms can include depression, constipation, sluggishness, dry skin and dry hair, and muscle cramps. Some people develop an enlarged thyroid, which leads to a swelling in the front of the neck known as a goiter.. 1  Previous.
Examples of oils containing Phenols â Wintergreen, Anise, Birch, Clove, Basil, Tarragon, Fennel, Oregano, Thyme, Mountain Savory, Peppermint, Tea Tree, Calamus, Cinnamon Bark, Citronella, Marjoram, Nutmeg, Eucalyptus citriodora, Parsley, Ylang Ylang. These all contain greater than 8% phenols.
Peppermint Oil and Phenols. The American Society for the Prevention of Cruelty to Animals states that cats are particularly sensitive to peppermint oil, noting the oil may cause harmful effects to the gastrointestinal system, central nervous system and liver. As well, inhaling the oil may cause aspiration pneumonia. However, the peppermint plant is not listed on the organization's toxic and nontoxic plant database as being safe -- or unsafe -- to pets. PetMD considers peppermint to be a cat-friendly plant, advocating it for home gardens.