Read the Patient Information Leaflet and Instructions for Use if available from your pharmacist before you start taking levothyroxine and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth as directed by your doctor, usually once daily on an empty stomach, 30 minutes to 1 hour before breakfast. Some brands may also be taken 15 minutes before breakfast. Ask your pharmacist about your brand of levothyroxine.

If you are using the medication that comes in a bottle, carefully measure the dose using a special measuring device/spoon. Do not use a household spoon because you may not get the correct dose. Take the medication directly from the measuring device. Do not mix with any other liquid.

If you are using the medication that comes in an ampule, the medication may be taken by first mixing it in water, or it may be taken directly (without water). To take it by mixing in water, open the ampule as directed. Then turn the ampule upside down and slowly squeeze the soft (middle) part of the ampule to empty the contents into a glass or cup of water. Release pressure and wait a few seconds. Repeat squeezing and releasing the ampule at least 5 times, until no more liquid comes out of the ampule. Stir the solution and drink all of the liquid right away. Rinse the glass or cup with more water and drink to make sure you have taken all the medicine. Do not prepare a supply ahead of time. To take this medication directly, slowly squeeze the soft (middle) part of the open ampule to empty the contents into the mouth or onto a spoon. Release pressure and wait a few seconds. Repeat squeezing and releasing the ampule at least 5 times, until no more liquid comes out of the ampule. Take all of the liquid right away.

The dosage is based on your age, weight, medical condition, lab test results, response to treatment, and other medications you may be taking. Be sure to tell your doctor and pharmacist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Use this medication regularly to get the most benefit from it. To help you remember, take it at the same time each day.

Do not stop taking this medication without consulting your doctor. Thyroid replacement treatment is usually taken for life.

There are different brands of levothyroxine available. Do not change brands without first consulting your doctor or pharmacist.

Certain medications (such as cholestyramine, colestipol, colesevelam, antacids, sucralfate, simethicone, iron, sodium polystyrene sulfonate, calcium supplements, orlistat, sucroferric oxyhydroxide, lanthanum, sevelamer, among others) can decrease the amount of thyroid hormone that is absorbed by your body. If you are taking any of these drugs, separate them from this medication by at least 4 hours.

Symptoms of low thyroid hormone levels include tiredness, muscle aches, constipation, dry skin, weight gain, slow heartbeat, or sensitivity to cold. Tell your doctor if your condition does not get better or if it gets worse after several weeks of taking this medication.