Levothyroxine Side Effects
What should I watch for?
Be sure to take this medicine with plenty of fluids. Some tablets may cause choking, gagging, or difficulty swallowing from the tablet getting stuck in your throat. Most of these problems disappear if the medicine is taken with the right amount of water or other fluids.
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.
Common and Rare Side Effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Chest pain or discomfort
decreased urine output
difficult or labored breathing
difficulty with swallowing
dilated neck veins
fast, slow, irregular, pounding, or racing heartbeat or pulse
pain or discomfort in the arms, jaw, back, or neck
swelling of the eyes, face, lips, throat, or tongue
tightness in the chest
Get emergency help immediately if any of the following symptoms of overdose occur:
Symptoms of overdose
Change in consciousness
cold, clammy skin
fast or weak pulse
loss of consciousness
sudden loss of coordination
sudden slurring of speech
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Abdominal or stomach cramps
change in appetite
false or unusual sense of well-being
fear or nervousness
feeling not well or unhappy
feeling of discomfort
feeling of warmth
feeling things are not real
feelings of suspicion and distrust
quick to react or overreact emotionally
rapidly changing moods
redness of the face, neck, arms, and occasionally, upper chest
trouble getting pregnant
trouble sitting still
unusual tiredness or weakness
weight gain or loss
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.