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Canadian Med Center

Your Guide to Taking Synthroid: Dosages and Instructions

Monday 17 June 2024
5 minute(s) read

Table of Contents

I. Finding the Right Synthroid Dosage

II. How to Take Synthroid Correctly

III. How to Maximize Synthroid’s Effectiveness

IV. Conclusion

Hypothyroidism impacts one in 300 people in the United States. [1] For most people with hypothyroidism, the gold-standard treatment is brand-name Synthroid or its generic counterpart, levothyroxine. [2]

When taken properly, Synthroid can be an effective treatment for hypothyroidism. However, to get the full benefits, it is important to take it at the right dosage and follow dosage adjustments as directed by your doctor.

In this article, we will walk you through how Synthroid works, how doctors determine your dosage and adjust it over time, the proper way to take Synthroid, and tips to maximize Synthroid’s effectiveness.

Finding the Right Synthroid Dosage

red tablet surrounded by white tablets

If you have been prescribed Synthroid, it's important to understand that it is a narrow therapeutic index (NTI) medication. This means that even a slight variation in dosage can cause a change in your thyroid hormone levels. [3]

Because of the precise dosing required, Synthroid offers twelve dosing options, each represented by a different colored tablet. This provides your doctor with the flexibility to find the right dose to get your thyroid levels in an optimal range. The goal is to give you the minimum dose that helps your thyroid levels. [3]

Synthroid dosing options include:

  • 25 mcg (orange tablet)
  • 50 mcg (white tablet)
  • 75 mcg (violet tablet)
  • 88 mcg (olive tablet)
  • 100 mcg (yellow tablet)
  • 112 mcg (rose tablet)
  • 125 mcg (brown tablet)
  • 137 mcg (turquoise tablet)
  • 150 mcg (blue tablet)
  • 175 mcg (lilac tablet)
  • 200 mcg (pink tablet)
  • 300 mcg (green tablet) [3]

While there are general guidelines for Synthroid dosages, your starting dose and titration schedule may differ if you have other medical conditions or if you are pregnant. However, a typical Synthroid dosing schedule is:

  • Starting dose: A full replacement dose is typically 1.6 mcg per kg of body weight per day. Some patients start lower.
  • Dose increases: Doses often increase by 12.5 to 25 mcg every four to six weeks until thyroid levels are optimal. Thyroid levels can be checked six to eight weeks after each change. [4]

Once your doctor has found the right Synthroid dose for you, it's important to have periodic tests to assess your treatment response. [3] Additionally, your treatment plan may need to be adjusted in the following conditions:

  • During pregnancy or breastfeeding: Your dose may need to increase to meet increased thyroid hormone needs.
  • Other medical conditions: Medications for heart disease, diabetes, blood clotting issues, or adrenal and pituitary problems may need dosage adjustment alongside Synthroid. [4]

How to Take Synthroid Correctly

Taking Synthroid consistently and correctly is crucial for its effectiveness. Synthroid works best when taken consistently and in the same way. Even small changes can impact how much of the medication your body absorbs.

  • Take your daily Synthroid dose at the same time: Taking Synthroid at the same time each day helps your body establish a routine.
  • Always take Synthroid on an empty stomach: Wait at least 30 minutes to an hour before eating breakfast or drinking anything other than water. This allows optimal absorption.
  • Only take Synthroid with water: Other beverages can interfere with its effectiveness.
  • Wait 30 to 60 minutes after taking Synthroid before consuming anything else: This ensures your body has time to fully absorb the medication. [5]

Establishing a routine is the best way to ensure you take Synthroid the same way every time. Try these tips:

  • Keep Synthroid in plain sight: Place your medication next to something you regularly use or see when you wake up, such as your phone, toothbrush, or keys.
  • Utilize sticky notes: Place reminders near your morning routine, such as on your phone or the morning newspaper, to prompt you to take your Synthroid.
  • Consider using a weekly pillbox: A pillbox can help you keep track of whether you have taken your Synthroid for the day.
  • Use visual cues as reminders: Create visual cues to indicate if you've taken your medication. For example, turn your medication bottle upside down after taking a dose. Then, before going to bed, turn it right side up, ready to use the next day.

How to Maximize Synthroid’s Effectiveness

patient consulting with a doctor

Synthroid can be a very effective treatment for hypothyroidism, but for it to work properly, you need to be aware of foods and medications that can interfere with its absorption and effectiveness.

Certain foods and ingredients can interfere with how well Synthroid works. [5] If you consume any of the following on a regular basis, let your doctor know so they can adjust your Synthroid dose:

  • Soy
  • Walnuts
  • Grapefruit juice
  • Cottonseed meal
  • Dietary fiber [5]

In addition, certain supplements and medications can affect Synthroid absorption if taken too close together. Avoid taking the following supplements four hours before or after taking a Synthroid dose: [5]

  • Iron supplements or multivitamins with iron
  • Calcium supplements or multivitamins with calcium
  • Antacids [5]

Balancing your thyroid doesn't stop with just taking Synthroid daily. You also need to:

  • Get your thyroid hormone levels checked as recommended by your doctor to ensure your Synthroid dosage is optimal.
  • Report any new symptoms or changes you notice to your doctor promptly.
  • If you have diabetes, monitor your blood sugar closely and notify your doctor about any changes.
  • Inform your doctor if you are or plan to become pregnant; your Synthroid dosage will likely need adjusting.
  • Be patient. It can take four to six weeks to feel the full effects of Synthroid. [3]


Treating hypothyroidism requires commitment and attentiveness on your part. Taking your Synthroid medication consistently and as prescribed by your doctor is crucial. However, you also need to be mindful of other factors that can interfere with Synthroid.

Pay close attention to your diet and try to limit or eliminate foods that can impact Synthroid’s absorption. Also, take inventory of any other medications you’re taking, as some drugs can interact with Synthroid. Don’t hesitate to consult your doctor about potential medication interactions.

The information provided is for informational purposes only. We do not offer medical advice. Please consult with your physician or qualified healthcare professional for guidance on drugs, medical conditions, or treatments. Our content is not a replacement for professional medical recommendations.