To return thyroid-stimulating hormone to normal levels, people with hypothyroidism can take a daily dose of oral levothyroxine, which is a synthetic thyroid hormone medication. To determine the proper dosage, doctors test an individual's TSH levels two to three months after beginning treatment. In general, people with hypothyroidism require life-long treatment with levothyroxine. As an alternative to synthetic thyroid medication, patients can take natural extracts containing thyroid hormone derived from pigs, according to Mayo Clinic.
Although treatment with the proper amount of levothyroxine normalizes thyroid hormone levels and does not usually cause side effects, taking larger doses can cause symptoms such as insomnia, shakiness, heart palpitations and increased appetite, notes Mayo Clinic. Normal TSH levels generally range from 0.4 to 4.0 milli-international units per liter, though this range may vary between laboratories, states WebMD.
Some foods and medications can interfere with the body's ability to absorb levothyroxine, warns Mayo Clinic. These include soy products, iron supplements, calcium supplements, cholestyramine and aluminum hydroxide. Other such medications include colestipol, sucralfate and antacids, which should be taken no sooner than four hours before or after taking levothyroxine to avoid interactions, notes Drugs.com
Some people may be allergic to levothyroxine, says Drugs.com. Signs of an allergic reaction requiring emergency medical assistance include swelling of the face, throat or tongue; hives; and difficulty breathing.
Patients should take levothyroxine first thing in the morning with a full glass of water, at least 30 minutes before eating breakfast, for maximum efficacy.