Highlights for levothyroxine
levothyroxine Side Effects
Side effects that you should report to your doctor or health care professional as soon as possible:
- allergic reactions like skin rash, itching or hives, swelling of the face, lips, or tongue
- chest pain
- excessive sweating or intolerance to heat
- fast or irregular heartbeat
- swelling of ankles, feet, or legs
Side effects that usually do not require medical attention (Report these to your doctor or health care professional if they continue or are bothersome.):
- changes in appetite
- changes in menstrual periods
- hair loss
- trouble sleeping
- weight loss
levothyroxine May Interact with Other Medications
- anti-thyroid medicines
- calcium supplements
- female hormones, including contraceptive or birth control pills
- iron supplements
- liquid nutrition products like Ensure
- medicines for colds and breathing difficulties
- medicines for diabetes
- medicines for mental depression
- medicines or herbals used to decrease weight or appetite
- phenobarbital or other barbiturate medications
- prednisone or other corticosteroids
- sodium polystyrene sulfonate
- soy isoflavones
How to Use levothyroxine
Take this medicine by mouth with a glass of water. It is best to take on an empty stomach, at least 30 minutes to one hour before breakfast. Avoid taking antacids containing aluminum or magnesium, simethicone, bile acid sequestrants, calcium carbonate, sodium polystyrene sulfonate, ferrous sulfate, and sucralfate within 4 hours of taking this medicine. Do not cut, crush or chew this medicine. Follow the directions on the prescription label. Take at the same time each day. Do not take your medicine more often than directed.
Talk to your pediatrician regarding the use of this medicine in children. While this drug may be prescribed for selected conditions, precautions do apply. Since the capsules cannot be crushed or placed in water, they may only be given to infants and children who are able to swallow an intact capsule.
They need to know if you have any of these conditions:
- blood clotting problems
- dieting or on a weight loss program
- fertility problems
- heart disease
- high levels of thyroid hormone
- pituitary gland problem
- previous heart attack
- an unusual or allergic reaction to levothyroxine, thyroid hormones, other medicines, foods, dyes, or preservatives
- pregnant or trying to get pregnant
If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.
Do not switch brands of this medicine unless your health care professional agrees with the change. Ask questions if you are uncertain.
You will need regular exams and occasional blood tests to check the response to treatment. If you are receiving this medicine for an underactive thyroid, it may be several weeks before you notice an improvement. Check with your doctor or health care professional if your symptoms do not improve.
It may be necessary for you to take this medicine for the rest of your life. Do not stop using this medicine unless your doctor or health care professional advises you to.
This medicine can affect blood sugar levels. If you have diabetes, check your blood sugar as directed.
You may lose some of your hair when you first start treatment. With time, this usually corrects itself.
If you are going to have surgery, tell your doctor or health care professional that you are taking this medicine.
Keep out of the reach of children.
Store at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light and moisture. Keep container tightly closed. Throw away any unused medicine after the expiration date.
Last Updated: March 11, 2010