Synthroid
® (
levothyroxine sodium) is a prescription medication that is a manufactured version of a certain thyroid hormone. Even though it is synthetic, the drug is identical to the naturally occurring hormone levothyroxine (also known as T
4). It is used to treat an
underactive thyroid (known medically as
hypothyroidism) and to treat a variety of thyroid problems (including certain
types of thyroid cancer).
Brand-name Synthroid is made by Abbott Laboratories.
The thyroid gland makes two different thyroid hormones: levothyroxine (T4) and triiodothyronine (T3). Typically, the thyroid produces much more T4 than T3 (however, T3 is much more active than T4). The body can convert the T4 hormone into T3 as necessary. If your thyroid does not make enough thyroid hormones, there are a few different ways to increase your levels.
Some forms of thyroid replacement combine T
4 and T
3 (such as natural thyroid replacement made from pig thyroids). However, because the body converts T
4 into T
3 as needed, most people can successfully take just T
4 (such as with Synthroid). Alternatively, just T
3 can be taken (as products such as
Cytomel®). Currently, most people take just T
4 (such as Synthroid).
When and How to Take Synthroid
General considerations for when and how to take Synthroid include the following:
- The medication comes in tablet form. It is usually taken once a day in the morning.
- It is best to take it on an empty stomach, 30 to 60 minutes before breakfast.
- If necessary (such as for young children), a Synthroid tablet may be crushed and mixed with one or two teaspoons of water. This mixture must be taken immediately (it should not be stored).
- Try to take your dosage at the same time each day to keep an even level in your blood.
- Your healthcare provider will adjust your dose based on certain blood tests. Be sure to tell your healthcare provider if you have missed any of your doses, as this may affect any dose adjustments.
- For the medication to work properly, it must be taken as prescribed. The drug will not work if you stop taking it.
Dosing Information for Synthroid
The dosage that your healthcare provider recommends will vary, depending on a number of factors, including:
- Your age
- Other medical conditions you may have
- The results of certain thyroid blood tests
- Any other medications you are taking.
As is always the case, do not adjust your dose unless your healthcare provider specifically instructs you to do so.
Side Effects of Synthroid
As with any medicine, side effects are possible. However, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. Serious side effects are less common.
Some of the possible side effects of Synthroid include, but are not limited to:
(Click Synthroid Side Effects to learn more, including potentially serious side effects that you should report immediately to your healthcare provider.)
Drug Interactions With Synthroid
What Should I Tell My Healthcare Provider Before Taking Synthroid?
You should talk with your healthcare provider prior to taking Synthroid if you have:
Also, let your healthcare provider know if you are:
Make sure to tell your healthcare provider about any other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
What If I Take an Overdose of Synthroid?
People who take too much Synthroid may have overdose symptoms that can include:
What Should I Do If I Miss a Dose of Synthroid?
If you forget to take your dose, take your missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular schedule. Do not take a double dose. Each time you get your blood tests to monitor your thyroid function, be sure to tell your healthcare provider if you have missed any doses, as this may affect any dose adjustments.
Synthroid tablets come in the following strengths (the colors of the tablets are in parentheses):
- 25 mcg (orange)
- 50 mcg (white)
- 75 mcg (violet)
- 88 mcg (olive)
- 100 mcg (yellow)
- 112 mcg (rose)
- 125 mcg (brown)
- 137 mcg (turquoise)
- 150 mcg (blue)
- 175 mcg (lilac)
- 200 mcg (pink)
- 300 mcg (green).
Sometimes, the strengths of Synthroid are given in milligrams (mg) instead of micrograms (mcg), which can be confusing. Because there are 1,000 mcg in every mg, Synthroid 100 mcg is the same thing as Synthroid 0.1 mg.
Is There a Generic Version of Synthroid?
Currently, there are several different generic versions of Synthroid available. However, you should not switch brands without first talking to your healthcare provider, as even tiny differences in this medication can result in large changes in the body. Not all
generic levothyroxine products are equivalent to Synthroid.
