Levothyroxine Dosage Guide: Dosing Starts Between 25-100 mcg - GoodRx (2024)

Levothyroxine (Levoxyl, Synthroid, Tirosint) is a lab-made form of thyroxine (T4), a thyroid hormone. It’s primarily used to treat low thyroid hormone levels (hypothyroidism). Levothyroxine helps restore your thyroid hormone levels when they’re lower than they should be.

This guide looks closer at the approved levothyroxine dosages for adults and children. Be aware that your healthcare provider may have you take levothyroxine differently than discussed below. If you have questions about how you’re taking levothyroxine, speak with your pharmacist or healthcare provider.

What’s the typical levothyroxine dosage for adults?

Your levothyroxine dose is calculated based on your body weight. For adults, it’s recommended to start with a levothyroxine dosage of 1.6 mcg per kg of body weight daily. Your healthcare provider will calculate your dose.

After 4 to 6 weeks, your healthcare provider will likely check your thyroid stimulating hormone (TSH) level. TSH levels go up when your thyroid hormone levels are too low, and come down when your thyroid levels are where they should be. Measuring your TSH is usually the best way to know how well your dose of levothyroxine is working.

Depending on your TSH level, your healthcare provider may make changes to your levothyroxine dosage. It’s recommended to only change the dose by 12.5 mcg to 25 mcg at a time. Once your TSH levels have stabilized, you’ll likely only need it tested once every 6 to 12 months.

What’s the typical levothyroxine dosage for children?

The levothyroxine dosage for children also depends on their weight and age. Since thyroid hormone plays a key role in growth and development, children have higher starting levothyroxine dosages than adults.

If you have trouble swallowing tablets, you can crush them and mix with 1 tsp to 2 tsp of water. Make sure to drink the mixture right away, and don’t make it in advance. And you shouldn’t mix crushed tablets with anything other than water.

A liquid formulation of levothyroxine is another alternative if you can’t swallow tablets or capsules. They may also be a better option if you can’t tolerate gluten or lactose, common ingredients in some tablets and capsules.

What’s the best way to take levothyroxine?

It’s best to take levothyroxine the same way every day. A change in how or when you take it can affect how you absorb the medication and make a big difference in how you feel. It’s often recommended to take levothyroxine first thing in the morning, about 30 to 60 minutes before your first meal of the day. But you can also take it in the evening, at least 2 hours after your last food of the day.

Other medications can also affect how much levothyroxine your body absorbs. It’s best to separate it from other medications by at least 4 hours.

Good to know: It’s best not to switch from one brand of levothyroxine to another, or from brand-name to generic versions. Minor differences in the formulation between brands can affect your thyroid hormone levels.

What happens if you miss a dose of levothyroxine?

If you miss your scheduled levothyroxine dose, take it as soon as you remember. But if it’s almost time for your next dose, skip the missed dose and just take your next one as scheduled. Don’t take two doses at the same time to make up for a missed dose.

If you miss multiple doses in a row, call your healthcare provider. They may adjust your dose for a short while to get your thyroid hormone levels back to normal. They can also suggest tips for remembering to take your medication.

What should you do if you take too much levothyroxine?

If you take an extra dose of levothyroxine by mistake, it’s not likely to cause a problem. But large amounts of levothyroxine can cause sweating, tremors, and trouble sleeping. It can also cause confusion. In rare cases, shock, coma, and even death can occur.

Good to know: Signs of a levothyroxine overdose can take several days to appear. So if you or a loved one takes too much levothyroxine, contact your healthcare provider or call Poison Control at 1-800-222-1222, even if you don’t notice any symptoms.

If you experience seizures, chest pain, or confusion after taking too much levothyroxine, seek medical care right away.

How to save on levothyroxine

There are many ways to save on your levothyroxine medication. GoodRx can help you navigate your options, which will vary based on the type and brand of medication you take.

GoodRx can help you save over 60% off the average retail price of the generic version. Generic levothyroxine’s price at certain pharmacies is as low as $8.08 with a free GoodRx discount.

There are also several copay savings cards available for the various brand-name versions of levothyroxine. If eligible, these copay cards can help you save on the following:

• Synthroid: Pay as little as $25 for a 30-day supply.

• Unithroid: Pay as little as $3 for a 30-day supply.

• Tirosint: Pay as little as $25 for a 30-day supply.

• Tirosint-SOL: Pay as little as $4 for a 30-day supply, or $0 for a 90-day supply.

• Thyquidity: Pay as little as $0 for your prescription.

• Ermeza: Pay as little $0 for your first prescription, and then $20 per month thereafter.

If you’re uninsured or underinsured, you may be eligible for Tirosint and Tirosint-Sol patient assistance programs, which offer the medication free of cost.