What are the side effects of levothyroxine? Is it safe to take it for life?
Will I have to take levothyroxine forever?
Your thyroid is a critical organ that makes thyroid hormones, which control energy production and consumption in your body. There are a lot of different things that can go wrong with the thyroid, resulting in being unable to make these very important thyroid hormones. In general, this condition is called hypothyroidism. The medicine, levothyroxine, replaces those thyroid hormones and regulates the energy needs of a person who no longer has a functioning thyroid.
Unfortunately, most of the problems that cause hypothyroidism are permanent. So, given how critical it is for you to have proper energy balance for your body, if you have hypothyroidism, you will need to take this medicine every day for the rest of your life. You can become very sick, and you can even die if you do not have enough thyroid hormones in your body or if you stop taking this medicine. You should definitely bring up all your questions and concerns about levothyroxine with your doctor. It’s important for you to feel comfortable taking this medicine.
Is it safe to take levothyroxine every day?
Levothyroxine is safe and necessary to take every single day when someone has hypothyroidism. It is important to see a doctor if you have thyroid problems or concerns about your thyroid. Levothyroxine has to be used at a certain dose to be safe and effective. Your healthcare provider needs to prescribe you this medicine, see how your body responds to it by checking your blood work, and then adjust the dose of the medicine, if necessary, so that it works properly with your body. When levothyroxine is taken this way, under the care of your physician, it is very safe and effective.
Are there any risks with taking levothyroxine for life?
There are certainly risks associated with any medication. The good news is that the risks are significantly lower when levothyroxine is taken under the care of a health provider. While taking this medicine, you may experience side effects that stem from taking too little or too much of a dose. Your healthcare provider will instruct you on how to increase or lower the dose to the right amount to keep you healthy. Most of the time when you are having side effects from this medicine, it is because your dose needs to be adjusted and you are getting too much of this medicine.
These side effects are uncommon but still possible:
- Heart symptoms and effects: chest pain, cardiac arrhythmia or irregular heartbeat, heart failure, flushing, high blood pressure, heart attack, palpitations, tachycardia or rapid heartbeat
- Brain and nervous system effects: anxiety, emotional lability or rapid mood changes, fatigue, headache, heat intolerance, hyperactivity, insomnia, irritability, myasthenia or muscle weakness, nervousness, pseudotumor cerebri or pressure around the brain (for children)
- Skin problems: alopecia, diaphoresis or excessive sweating, rash
- Endocrine and metabolic: goiter, menstrual problems, weight loss
- Gastrointestinal issues: cramps, diarrhea, increased appetite, vomiting
- Genitourinary problems: reduced fertility
- Increased liver enzymes
- Muscle side effects: decreased bone mineral density, muscle spasm, slipped capital femoral epiphysis or hip disorder (children), tremor
- Respiratory: trouble breathing
- Miscellaneous: fever
- Rare (<1%): altered taste, seizure
Can I use levothyroxine to lose weight?
When someone’s thyroid is too active and there is too much thyroid hormone in the body, a common symptom is weight loss. So some people have looked at this as a possible weight loss solution.
You might lose some weight by taking levothyroxine (though it is not guaranteed), but you will certainly expose yourself to serious harm. If this medicine is taken in excess or abused, you can have serious side effects — most serious of all perhaps are the heart-related problems. This medicine, when used incorrectly, can cause deadly heart rhythms to develop, chest pains, heart attack, and even death. It is not safe or recommended to use this medicine in any way as a means to lose weight.
What interacts with levothyroxine? Will my other medicines and supplements affect my levothyroxine?
Certain foods, medicines, and supplements can interfere with how your body absorbs levothyroxine. So there are quite a few things that interact with levothyroxine that are important to know. The best practice is to take levothyroxine first thing in the morning, on an empty stomach, and at least 30 minutes before you eat. You can take the medicine at night too, but you really want to wait at least 4 hours after your last meal.
Some will need to take this medicine with food or they may feel sick to their stomach. If that is the case, there are three major categories you want to avoid: 1) medicines/supplements or foods that contain calcium, 2) anything that has iron, and 3) special medicines called bile acid sequestrants, like cholestyramine, which is a medicine used to lower cholesterol. These different foods or medicines can really impact how your body is able to get and use the levothyroxine that you are prescribed. These foods, supplements, and medicines can make levothyroxine much less effective.
There are quite a few medicines that can impact your levothyroxine if you take them together. You need to make sure that the doctor who prescribes your levothyroxine knows about all the medicines and supplements you take.
Some common medicines (not a complete list) that can affect the amount of levothyroxine or can be affected by levothyroxine are as follows: aluminum hydroxide (antacids), amezinium, amiodarone, apalutamide, bile acid sequestrants, calcium polystyrene sulfonate, calcium salts, carbamazepine, ciprofloxacin, estrogen derivatives, fosphenytoin and phenytoin, iron preparations, lanthanum, magnesium salts, multivitamins/minerals (those that have vitamins A, D, E, or K, and folate or iron), orlistat, patiromer, piracetam, polaprezinc, raloxifene, rifampin, ritonavir, selective serotonin reuptake inhibitors, semaglutide, sevelamer, sodium iodide i 131, sodium polystyrene sulfonate, somatropin, sucralfate, sucroferric oxyhydroxide, theophylline derivatives, tricyclic antidepressants, and vitamin K antagonists (like warfarin)
Is levothyroxine safe to use if I am pregnant?
Great question! Levothyroxine is not only safe during pregnancy but it also protects you and your baby during pregnancy. There are no known birth defects or harm that occurs when women take levothyroxine during pregnancy. And if a pregnant woman needs levothyroxine but is not taking it during pregnancy, both she and her baby can be harmed. Blood work needs to be monitored closely to make sure that a pregnant woman is on the right dose of levothyroxine. Sometimes the dose needs to be adjusted to a higher or lower dose during pregnancy, even when that dose was working well before getting pregnant.