Synthroid Warnings and Precautions
To help ensure a safe and effective treatment process with Synthroid, warnings and precautions should be reviewed with your healthcare provider. For instance, prior to taking Synthroid, tell your healthcare provider if you have any heart problems, diabetes, or osteoporosis. Synthroid warnings and precautions also apply to people who have untreated adrenal insufficiency, an overactive thyroid, or a recent history of heart attack.
You should talk with your healthcare provider prior to taking Synthroid® (levothyroxine sodium) if you have:
- An overactive thyroid (hyperthyroidism)
- A recent history of heart attack
- Adrenal insufficiency
- Any heart problems
- Any allergies, including allergies to food, dyes, or preservatives.
Also, let your healthcare provider know if you are:
- Pregnant or thinking of becoming pregnant
Make sure to tell your healthcare provider about any other medicines you are taking, including prescription and non-prescription medicines, vitamins, and herbal supplements.
Warnings and precautions to be aware of prior to taking Synthroid include the following:
- People who do not have thyroid problems should never use Synthroid to lose weight. A Synthroid dosage high enough to cause weight loss in such people is often high enough to cause serious or even life-threatening problems.
- Synthroid should not be used to treat goiters or thyroid nodules in people who have a low level of thyroid-stimulating hormone (TSH), as it could cause dangerous side effects. A low TSH level signals that thyroid hormone levels are already high, and adding Synthroid could cause them to increase to a dangerous level. Even if the TSH level is normal, frequent monitoring is required to make sure problems do not develop.
- Synthroid is a "narrow therapeutic index" medication. This means that for any given person, the range of Synthroid doses that are both safe and effective is small. Even tiny changes in doses can cause significant problems (either making Synthroid ineffective or causing serious side effects). Your healthcare provider should carefully and slowly adjust your dose, and should monitor your progress often using blood tests. Even if you have been stable on Synthroid for years, your healthcare provider should still do these blood tests regularly.
- Synthroid may increase the risk of osteoporosis, particularly if your Synthroid dose is too high. This is one of the reasons why it is a good reason for your healthcare provider to prescribe a dose of Synthroid that is just enough to return your thyroid hormone levels to normal.
- The medication can make heart problems worse. If you have heart problems, your healthcare provider should start you at a low Synthroid dosage and slowly increase it. If you notice that Synthroid makes your heart symptoms worse, let your healthcare provider know right away.
- Sometimes, thyroid problems occur in conjunction with other health problems (such as anemia or diabetes). It is a good idea for your healthcare provider to give you a thorough physical when you are diagnosed with a thyroid problem.
- It often takes Synthroid several weeks to start working. Try not to get frustrated if you are not feeling better more quickly.
- If you have diabetes, it is a good idea to check your blood sugar more often when starting or stopping Synthroid (or when changing your dose), as the medication can affect your blood sugar.
- Synthroid can potentially interact with many other medications (see Synthroid Drug Interactions).
- Synthroid is considered a pregnancy Category A medication. This means that it is safe for use during pregnancy (see Synthroid and Pregnancy).
- Synthroid does pass through breast milk in humans, although it is not likely to cause problems. Therefore, if you are breastfeeding or plan to start, discuss this with your healthcare provider prior to taking the drug (see Synthroid and Breastfeeding).