Synthroid (Levothyroxine) is used to treat an underactive thyroid (hypothyroidism). Synthroid replaces or provides more thyroid hormone, which is normally produced by the thyroid gland. Low thyroid hormone levels can occur naturally or when the thyroid gland is injured by radiation/medications or removed by surgery. It is important to have enough thyroid hormone in the body for maintaining normal mental and physical activity. In children, having enough thyroid hormone is important for normal mental and physical development. It may take several weeks before you notice an improvement in your symptoms.

This medication is also used to treat other types of thyroid disorders (such as certain types of goiters, thyroid cancer).

Take this medication by mouth as directed by your doctor, usually once daily on an empty stomach, 30 minutes to 1 hour before breakfast. Take this medication with a full glass of water unless your doctor directs you otherwise.

Foods containing soy and cottonseed meal can make Synthroid less effective. Walnuts, grapefruit juice, and dietary fibre can also make Synthroid less effective. If you eat any of these on a regular basis, check with your doctor. He or she may need to adjust your dose of Synthroid. Some supplements and medications can also interfere with the way Synthroid works. To avoid this, you should take Synthroid 4 hours before or after taking:

• Iron supplements and multivitamins with iron

• Calcium supplements or multivitamins with calcium

• Antacids

If you are taking the capsule form of this medication, swallow it whole. Do not split, crush, or chew. People who cannot swallow the capsule whole (such as infants or small children) should use the tablet form of the medication.

For infants or children who cannot swallow whole tablets, crush the tablet and mix in 1 to 2 teaspoons (5 to 10 milliliters) of water, and give using a spoon or dropper right away. Do not prepare a supply in advance or mix the tablet in soy infant formula.

This medication should not be used for weight loss. Normal doses of this medication will not work for weight loss, and large doses of this medication may cause serious, possibly fatal side effects, especially when taken with diet pills.

Before taking levothyroxine, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Before using this medication, tell your doctor or pharmacist your medical history, especially of: increased thyroid hormones (thyrotoxicosis), decreased adrenal gland function, heart disease (such as coronary artery disease, irregular heartbeat), high blood pressure, diabetes.

Hair loss may occur during the first few months of treatment. This effect is usually temporary as your body adjusts to this medication. If this effect persists or worsens, tell your doctor or pharmacist promptly. Tell your doctor if you develop any of the following symptoms:

-Rapid or abnormal heartbeat

-Chest pain, difficulty catching your breath

-Leg cramps

-Headache

-Nervousness

-Irritability

-Sleeplessness

-Shaking

-Change in appetite

-Weight gain or loss

-Vomiting

-Diarrhea

-Increased sweating

-Difficulty tolerating heat

-Fever

-Changes in menstrual periods

-Swollen red bumps on the skin (hives) or skin rash

-Any other unusual medical event.

What do I do if I miss a dose?

It is important to take Synthroid exactly as your doctor prescribed. If you miss a dose, speak with your doctor for advice on what to do.

Can I take Synthroid at a later time on weekends and holidays?

You should take Synthroid the same way every day as your doctor prescribed.

What do I do if I’m travelling to another time zone?

When travelling to another country or time zone, ask the doctor or pharmacist if you need to adjust the time of day that you take Synthroid. Remember to pack more tablets than you need in your carry-on bag or purse in case you get delayed or decide to stay longer.