Thyroid hormone (also known as levothyroxine) is a prescription medicine to treat a condition called hypothyroidism. When a child has this condition, their body doesn’t make enough thyroid hormones. This medicine replaces the thyroid hormones that the child’s body doesn’t make.

Babies and children need thyroid hormones to grow and develop normally. Thyroid hormones affect every cell and all the organs of the body. They affect many functions, including heart rate, body temperature, and muscle strength. They are also important for metabolism, the body’s process of turning food into energy.

This medicine is most widely available in pill form.

For babies and small children:

1. Crush the pill just before giving it.
2. Mix the crushed pill into a small amount of water, breast milk, or formula. (Don’t pre-mix and store the crushed pill and liquid, because it may not have the proper effect when pre-mixed.)
3. Give the mixed liquid using a spoon, dropper, or syringe.
4. Add a little more water to the spoon, dropper, or syringe 2 more times and give it again. This is to make sure that the child gets the full dose.

For older children and teens, have them swallow the pills whole with water. They can also chew the pills if they have trouble swallowing them.

Give this medicine every day at the same time. It can help to get a 7-day pillbox and fill it at the start of the week. If you miss one dose, give it as soon as possible. If you miss a whole day, you can give two doses the next day—one in the morning and one in the evening. Do not give both doses at the same time.

If your child takes the medicine every day as directed, they should live a healthy, normal life. The doctor will do regular blood tests to make sure that your child is getting the right dose. The doctor will change the dose if needed.

Some medicines can change how much thyroid medicine your child needs. These include birth control pills and some medicines used for seizures. Always tell your child's doctor or pharmacist about all medicines and supplements your child takes.

Certain foods and supplements can block the body from absorbing thyroid medicine. Make sure that your child doesn't have these items along with the medicine:

• Soy protein formulas or soy milk
• Concentrated iron
• Calcium supplements and aluminum hydroxide
• Fiber supplements
• Sucralfate

Choose whether your child will take the medicine with or without food, and then stick with this choice long-term. If the medicine is sometimes taken on a full stomach and sometimes on an empty stomach, how much of it is absorbed by the body could change day to day.

Side effects only happen if a child takes too much medicine. They may have a fast heart rate, sweating, anxiety, and shaking of the hands, head, or voice. Contact the doctor if you notice any of these symptoms.