This information from Lexicomp® explains what you need to know about this medication, including what it’s used for, how to take it, its side effects, and when to call your healthcare provider.
Euthyrox; Levoxyl; Synthroid; Tirosint; Tirosint-SOL; Unithroid; Unithroid Direct
- Do not use this drug to treat obesity or for weight loss. Very bad and sometimes deadly side effects may happen with this drug if it is taken in large doses or with other drugs for weight loss. Talk with the doctor.
- It is used to add thyroid hormone to the body.
- It is used to manage thyroid cancer.
- It may be given to you for other reasons. Talk with the doctor.
- If you have an allergy to levothyroxine or any other part of this drug.
- If you are allergic to any drugs like this one, any other drugs, foods, or other substances. Tell your doctor about the allergy and what signs you had, like rash; hives; itching; shortness of breath; wheezing; cough; swelling of face, lips, tongue, or throat; or any other signs.
- If you have any of these health problems: Overactive thyroid gland or weak adrenal gland.
Tablets and capsules:
- If you have trouble swallowing.
This is not a list of all drugs or health problems that interact with this drug.
Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take this drug with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.
For all patients taking this drug:
- Tell all of your health care providers that you take this drug. This includes your doctors, nurses, pharmacists, and dentists.
- Do not run out of this drug.
- It may take several weeks to see the full effects.
- If you have high blood sugar (diabetes), this drug may sometimes raise blood sugar. Talk with your doctor about how to keep your blood sugar under control.
- Check your blood sugar as you have been told by your doctor.
- Have blood work checked as you have been told by the doctor. Talk with the doctor.
- This drug may cause weak bones (osteoporosis) with doses that are too high. The risk may be higher in women who have been through menopause. Talk with your doctor to see if you have a higher risk of weak bones or if you have any questions.
- This drug may affect how much of some other drugs are in your body. If you are taking other drugs, talk with your doctor. You may need to have your blood work checked more closely while taking this drug with your other drugs.
- This drug may affect fertility. Fertility problems may lead to not being able to get pregnant or father a child. Talk with the doctor.
- If you are 65 or older, use this drug with care. You could have more side effects.
- Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using this drug while you are pregnant.
- Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.
- If giving to your child, the dose of this drug may need to be changed as your child’s weight changes. Have your child’s weight checked often. Talk with the doctor before changing your child’s dose.
- This drug may affect growth in children and teens in some cases. They may need regular growth checks. Talk with the doctor.
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Signs of high blood pressure like very bad headache or dizziness, passing out, or change in eyesight.
- Chest pain or pressure or a fast heartbeat.
- A heartbeat that does not feel normal.
- Shortness of breath, a big weight gain, or swelling in the arms or legs.
- Feeling tired or weak.
- Feeling more or less hungry.
- A change in weight without trying.
- Stomach cramps.
- Throwing up.
- Feeling irritable.
- Feeling nervous and excitable.
- Emotional ups and downs.
- Trouble sleeping.
- Bothered by heat.
- Sweating a lot.
- Leg cramps.
- Muscle weakness.
- Bone pain.
- Period (menstrual) changes.
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
- Hair loss may happen in some people in the first few months of using this drug. This most often goes back to normal.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to your national health agency.
Use this drug as ordered by your doctor. Read all information given to you. Follow all instructions closely.
All oral products:
- Take on an empty stomach at least 30 to 60 minutes before breakfast.
- Do not take iron products, antacids that have aluminum or magnesium, or calcium carbonate, within 4 hours before or 4 hours after taking this drug.
- If you take colesevelam, colestipol, cholestyramine, kayexalate, or sevelamer, take it at least 4 hours before or 4 hours after taking this drug.
- Some other drugs may need to be taken at some other time than this drug. If you take other drugs, check with your doctor or pharmacist to see if you need to take them at some other time than this drug.
- Some foods like soybean flour (infant formula) may change how this drug works in your body. Talk with your doctor.
- If you drink grapefruit juice or eat grapefruit often, talk with your doctor.
- To gain the most benefit, do not miss doses.
- Keep taking this drug as you have been told by your doctor or other health care provider, even if you feel well.
- Swallow capsule whole. Do not chew, break, or crush.
- Some products may cause choking, gagging, or trouble swallowing. These products must be taken with a full glass of water. Ask your pharmacist if you need to take your product with a full glass of water.
- You may crush tablet and mix with 1 or 2 teaspoons (5 or 10 mL) of water.
Tablets and capsules:
- There is more than 1 brand of this drug. One brand cannot safely be used for the other. The doctor will tell you about any needed change.
- You may put this drug right in your mouth or you may mix it with water. If mixing with water, empty the contents into a cup with water in it. Squeeze the container over the cup at least 5 times until no more drug comes out. Stir well.
- After mixing, take your dose right away. Do not store for future use.
- Rinse cup with more water and drink.
- Take with water only; do not take with other drinks.
- It is given as a shot into a vein.
All oral products:
- Take a missed dose as soon as you think about it.
- If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
- Do not take 2 doses at the same time or extra doses.
- Call your doctor to find out what to do.
All oral products:
- Store at room temperature.
- Protect from heat and light.
- Store in a dry place. Do not store in a bathroom.
- Do not take this drug out of the blister pack until you are ready to take it. Take this drug right away after opening the blister pack. Do not store the removed drug for future use.
- Some brands of this drug come in a blister pack. If this drug comes in a blister pack, do not take it out of the blister pack until you are ready to take it. Do not store the removed drug for future use.
- Store in protective pouch until ready for use.
- Throw away 15 days after opening the pouch.
- If you need to store this drug at home, talk with your doctor, nurse, or pharmacist about how to store it.
- Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
- Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.
- If your symptoms or health problems do not get better or if they become worse, call your doctor.
- Do not share your drugs with others and do not take anyone else’s drugs.
- Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
- Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
- Some drugs may have another patient information leaflet. If you have any questions about this drug, please talk with your doctor, nurse, pharmacist, or other health care provider.
- If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.
This information should not be used to decide whether or not to take this medicine or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.
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