Many medications can have a negative impact on thyroid function. For example, thyroid dysfunction often accompanies the debilitating brain and muscle side effects that have occurred in women who have received the hormone-suppressing drug Lupron or the HPV vaccine Gardasil.

These side effects are unusually similar to the inflammatory symptoms that accompany multiple sclerosis (MS). Years of animal research have demonstrated an improvement in MS symptoms after triiodothyronine (T3) administration. T3 seems to put the brakes on damage to the nerve sheath and actually promotes healing of the nerve.

People with inflammatory nerve conditions, who are also experiencing hypothyroid symptoms, may benefit from taking T3. Levothyroxine (T4) alone may not be enough, as studies have shown that critically ill patients with low thyroid function do not benefit from taking just T4.