Levothyroxine is used to stimulate an underactive thyroid, or hypothyroidism. This medication contains a synthetically produced replacement for the thyroid hormone which can supplement or replace the body's natural stores. Levothyroxine is prescribed when the thyroid has become damaged due to surgery, radiation, other medications or in the event that the thyroid must be removed.
Levothyroxine is intended to be used alongside other forms of treatment including diet and exercise to maintain the healthiest levels of thyroid function possible. This medication cannot be used to promote weight loss or infertility unless these issues are stemming directly from poor thyroid function. Taking levothyroxine alongside diet pills can cause dangerous and potentially deadly side effects.
Side Effects of Levothyroxine
In general, levothyroxine is well tolerated in patients. Most side effects stem from overusing the drug or using it incorrectly. Follow all instructions from your doctor when using levothyroxine and ask questions about anything you do not understand.
Common side effects of levothyroxine include heat intolerance, anxiety, increased appetite, weight loss, insomnia, diarrhea, palpitations, tachycardia, hypertension, angina, increased bowel frequency and menstrual irregularities. These side effects typically appear several weeks after starting your medication.
In the event that a patient is allergic to one or more ingredients in levothyroxine, an allergic reaction may occur. Symptoms of such a reaction include hot flashes or sweating, changes in menstrual periods, appetite or weight changes, sleep problems, headaches, pounding heartbeats, a fluttering sensation in the chest, a nervous or irritable feeling and mild hair loss. Contact your doctor right away if any such symptoms occur after taking your medication.
In the event of a serious allergic reaction you may experience difficulty breathing, swelling of the lips, throat, tongue or face and hives. Contact emergency medical services immediately when any of these side effects occur.
Cardiovascular symptoms including angina, tachycardia, palpitations and hypertension have been reported in clinical trials when testing levothyroxine. Patients that already suffered from an underlying cardiovascular condition or disorder including heart disease or decreased cardiovascular function were significantly more likely to develop such side effects. Those with enhanced left ventricular systolic function and increased left ventricular mass index are also at high risk for developing cardiovascular side effects while using this medication.
Those using levothyroxine have reported changes in their endocrine function. This may include adrenal cortical insufficiency or an increased presence of diabetes symptoms. Those who are already at risk for developing such conditions should talk to their doctor about any potential risk before starting regular doses of levothyroxine.
Nervous System Effects
Neurological side effects to levothyroxine are somewhat rare. Some have reported experiencing seizures during the start of their therapy, but these usually taper after a few months.
Levothyroxine has also been reported to cause muscle weakness or hyperactivity in some patients. This can lead to crankiness or unexplained irritability.
Mild hair loss is frequently reported when using levothyroxine. This side effect is not dangerous and typically stops after the body becomes used to these altered hormone levels. Transient dermatologic effect has also been reported in the initial months of using the drug.
Studies have shown that long-term use of levothyroxine may lead to an increased risk for osteoporosis, particularly in those that are already at risk for developing the condition. The rates of femur fractures are larger in those using thyroid therapy than those that do not, especially in women. Patients have reported feeling as though their bones are more brittle or becoming more prone to injury after using levothyroxine for long periods of time.
Precautions of Using Levothyroxine
Obesity - Levothyroxine is not intended to be used to treat obesity, particularly in children. If you will be giving levothyroxine to a child that is still developing you will need to work closely with your doctor to determine a proper dose. You may need to have regular blood tests taken to ensure that no dangerous long term effects are developing. Watch for side effects that indicate that your child is dealing with an unhealthy reaction to levothyroxine. These include chest pain, irregular heartbeat, rapid heartbeat, shortness of breath, tremors, leg cramps, nervousness, irritability, sleeplessness, changes in appetite, headaches, diarrhea, weight gain or loss, vomiting, fever, heat intolerance, hives, rash or changes in menstrual periods.
Infertility and pregnancy - In some cases, using levothyroxine can cause infertility. This medication is not intended to be used to treat infertility in men or women and can cause dangerous side effects when used as such. Those with low fertility levels should talk to their doctor about any potential risks before starting their medication. You should also avoid using this medication while you are pregnant.
Preexisting conditions - Those with preexisting conditions that may conflict with the medication should talk to their doctor before agreeing to use levothyroxine. Patients with diabetes are at a high risk for developing side effects that could be fatal. Also inform your doctor if you have warning signs of developing osteoporosis.
Medications and sugary - Inform any other doctors you see that you are taking levothyroxine. This includes your dentist. This will allow them to determine if it is safe to treat you with medications such as anesthesia. You may need to stop using your medication several days before having medical tests or surgery to minimize your risk of a negative reaction. Talk to your doctor about any other medications you are taking before you start using levothyroxine to ensure that you are not at risk for overdosing on certain ingredients. This includes any supplements that you take on a regular basis.