Euthyrox 25: Uses, Contraindications, Administration, Warnings, Side Effects and Interactions

It is given when the thyroid does not make enough of this hormone on its own.

Euthyrox 25 (levothyroxine) treats hypothyroidism (low thyroid hormone).

Contraindications of Euthyrox 25

You should not use this medicine if you have had a heart attack, a thyroid disorder called thyrotoxicosis, or an adrenal gland problem that is not controlled by treatment.

Before taking this medication, tell your doctor if you have heart disease, coronary artery disease, anemia (lack of red blood cells), diabetes, problems with the pituitary or adrenal gland, or a history of blood clots.

If you use insulin or take oral diabetes medications , ask your doctor if your dose needs to be changed when you start using levothyroxine.

Levothyroxine is classified by the FDA in category A for Pregnancy Hazards. This means that it is safe to use while you are pregnant. It is also safe to use while breastfeeding a baby.

Tell your doctor if you become pregnant during treatment. Your dose may need to be increased during pregnancy or if you plan to breastfeed.

In most cases, you will need to take levothyroxine for the rest of your life. Talk to your doctor about how this might affect you.


Take Euthyrox 25 exactly as your doctor has prescribed it for you. Do not use more medicine than recommended. Do not take Euthyrox 25 for longer than your doctor has prescribed.

Your doctor may occasionally change your dose to make sure you get the best results from this medicine.

It is very important to take Euthyrox 25 with a full glass (8 ounces) of water. The levothyroxine tablet can dissolve very quickly and swell in the throat, possibly causing choking or gagging.

Take this medicine on an empty stomach, 30 minutes before eating. Euthyrox 25 is generally taken in the morning.

Follow your doctor’s dosing instructions and try to take this medicine at the same time each day.

It may take several weeks before your body begins to respond to this medicine.

Do not stop taking this medicine suddenly. Even if you feel fine, you may still need to take this medicine every day for the rest of your life to replace the thyroid hormone that your body cannot make.

To make sure this drug is helping your condition, your blood will need to be tested regularly. Your kidney or liver function may also need a test.

It is important that you do not miss any scheduled visits to your doctor.

Tell any doctor or dentist who treats you that you are using Euthyrox 25.

Store the medicine away from moisture and heat.

Missed dose

Take the missed dose when you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at the next regularly scheduled time. Do not take any additional medications to make up for the missed dose.

Excess dose

Seek immediate medical attention if you have used too much of this medicine.

Overdose symptoms may include chest pain, pounding heartbeat, shortness of breath, tremors, leg cramps, confusion, vomiting, diarrhea, or seizures.


Do not switch brands or switch to a generic levothyroxine drug without first checking with your doctor.

Different brands of levothyroxine may not work in the same way. If you get a refill on your prescription and your new pills look different, talk to your pharmacist or doctor.

Avoid the following food products, which can make your body absorb less levothyroxine: soy infant formula, cottonseed meal, walnuts, and high-fiber foods.

Side effects of Euthyrox 25

Call your doctor right away if you have any of these serious side effects:

  • Headache.
  • Trouble sleeping (insomnia).
  • Nervous or irritable feeling
  • Fever, hot flashes, sweating.
  • Changes in your menstrual periods.
  • Changes in appetite and weight changes.
  • Less serious side effects can include mild hair loss.

This is not a complete list of side effects and others may occur. Tell your doctor about any unusual or bothersome side effects.


The following medications can cause medical problems if you use them with levothyroxine: lithium, amiodarone, or antidepressants. Tell your doctor if you have recently received radiation therapy with iodine (such as I-131).

This list is not complete and there are many other drugs that can interact with Euthyrox 25. Tell your doctor about all the prescription and over-the-counter medications you use.

This includes vitamins, minerals, herbal products, and medications prescribed by other doctors. Don’t start using a new medicine without telling your doctor.

Certain medications can be continued, but they can make levothyroxine less effective if taken at the same time. If you use any of the following medications, use them at least 4 hours before or 4 hours after taking Euthyrox 25:

  • Calcium carbonate (Caltrate, Citracal, Oystercal, and others).
  • Ferrous sulfate iron supplement.
  • Sucralfato (Carafate).
  • Sodium polystyrene sulfonate (Kayexalate, Kionex and others).
  • Cholestyramine (Questran) and colestipol (Colestid) cholesterol-lowering drugs.