To return to the main entry click here.
What is levothyroxine injection?
LEVOTHYROXINE (Synthroid®, Levothroid®) acts as a replacement for people whose thyroid gland does not produce enough thyroid hormone. Levothyroxine can improve symptoms of thyroid deficiency such as slow speech, lack of energy, weight gain, hair loss, dry thick skin and unusual sensitivity to cold. Levothyroxine also helps to treat a condition called goiter, which is an enlarged thyroid gland. Generic levothyroxine injections are available.
What should I tell my health care provider before I take this medicine?
They need to know if you have any of these conditions:
• angina
• diabetes mellitus
• heart disease
• high blood pressure
• low levels of pituitary hormone
• dieting or on a weight loss program
• previous heart attack
• an unusual or allergic reaction to levothyroxine, other thyroid hormones, medicines, foods, dyes, or preservatives
• pregnant or trying to get pregnant
How should I use this medicine?
Levothyroxine is for injection into a muscle or into a vein by a health care professional. For regular control of thyroid deficiency the injection is usually given into a muscle.
Contact your pediatrician or health care professional regarding the use of this medicine in children. Special care may be needed.
What drug(s) may interact with levothyroxine?
• amiodarone
• carbamazepine
• digoxin
• female hormones, including contraceptive or birth control pills
• ketamine
• 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
• phenytoin
• prednisone or other corticosteroids
• rifabutin
• rifampin
• soy isoflavones
• theophylline
• warfarin
Tell your prescriber or health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, or herbal products. Also tell your prescriber or health care professional if you are a frequent user of drinks with caffeine or alcohol, if you smoke, or if you use illegal drugs. These may affect the way your medicine works. Check with your health care professional before stopping or starting any of your medicines.
What should I watch for while taking levothyroxine?
If you are receiving levothyroxine for an underactive thyroid, it may be several weeks before you notice an improvement. Check with your prescriber or health care professional if your symptoms do not improve or if you develop any of the above side effects. It may be necessary for you to take this medicine for the rest of your life; do not stop using except on your prescriber's advice.
Thyroid hormones can affect blood sugar levels. If you also have diabetes, you may need to adjust the dose of your diabetic medicine once you are stabilized on levothyroxine.
You may lose some of your hair while using levothyroxine. With time, this usually corrects itself.
If you are going to have surgery, tell your prescriber or health care professional that you are taking levothyroxine.
What side effects may I notice from receiving levothyroxine?
Side effects that you should report to your prescriber or health care professional as soon as possible:
• difficulty breathing, wheezing, or shortness of breath
• chest pain
• excessive sweating or intolerance to heat
• fast or irregular heartbeat or pulse rate
• nervousness
• skin rash or hives
• swelling of ankles, feet or legs
Side effects that usually do not require medical attention (report to your prescriber or health care professional if they continue or are bothersome):
• changes in appetite
• changes in menstrual periods
• diarrhea
• fever
• hair loss
• headache
• irritability
• leg cramps
• nausea, vomiting
• tremors
• trouble sleeping
• weight loss
Where can I keep my medicine?
Keep out of the reach of children in a container that small children cannot open.
Store undiluted injection at room temperature between 15 and 30 degrees C (59 and 86 degrees F). Protect from light. Throw away any unused medicine after the expiration date. Once diluted, any unused injection should be discarded.
Important Disclaimer: The drug information provided here is for educational purposes only. It is intended to supplement, not substitute for, the diagnosis, treatment and advice of a medical professional. This drug information does not cover all possible uses, precautions, side effects and interactions. It should not be construed to indicate that this or any drug is safe for you. Consult your medical professional for guidance before using any prescription or over the counter drugs.
