Key takeaways

Synthroid (levothyroxine) requires consumption on an empty stomach with water to avoid rapid dissolution and improper absorption, not with coffee or other substances.
Consuming coffee immediately after taking Synthroid can lead to inadequate absorption of the medication, potentially resulting in undertreatment of thyroid conditions.
Certain foods and substances, including walnuts, soybean flour, cottonseed meal, dietary fiber, and grapefruit juice, can negatively impact Synthroid absorption.
Other medications, especially those containing calcium, iron, antacids, and some prescriptions, can interfere with Synthroid absorption, necessitating a spacing of doses by four hours.

Synthroid (levothyroxine) is a drug commonly prescribed to treat hypothyroidism, certain types of goiters, or thyroid cancer. It replaces thyroid hormone that your body is meant to produce on its own—but doesn’t due to disease. This medication can help you stay healthy when this small, butterfly-shaped gland malfunctions.

Thyroid medications work best when you take them on an empty stomach—for at least 30 to 60 minutes. That’s the main reason why many people take this prescription first thing in the morning. However, there’s another substance many people use just after waking up: coffee. Is it safe to mix Synthroid and caffeine?

Is it safe to take Synthroid and coffee together?

Synthroid is best taken with a full 8-ounce glass of water. Otherwise, the medication could dissolve quickly and swell in your throat. Chasing your pill with a cup of coffee instead can mean that your body doesn’t absorb the medication properly.

“This effect does not last long, but can lead to undertreatment of your thyroid condition,” says Nisha Jayani, MD, board-certified endocrinologist with Paloma Health in Arizona. Meaning, you’re not getting enough of the prescription to alleviate your symptoms. You may not feel well, or experience fatigue, mood issues, and other side effects of an underactive thyroid.

Fortunately, you won’t have to wait too long for your morning caffeine fix. “You can drink coffee an hour after taking levothyroxine,” says Anthony Puopolo, MD, chief medical officer at LifeMD. So, take your pill when you wake up and set a timer for 60 minutes before diving into the coffee pot.

What other foods should you avoid when taking Synthroid?

Even if you’re not a coffee drinker, there are certain things that can affect how well Synthroid works. According to DailyMed, the following foods can make it harder for your body to absorb Synthroid:

Walnuts
Soybean flour
Cottonseed meal
Dietary fiber

Examples of foods that are high in dietary fiber include beans, broccoli, apples, berries, avocados, and quinoa.

Grapefruit juice can also inhibit the effectiveness of your medication by potentially decreasing the absorption of Synthroid. If you consume these foods, ask your healthcare provider if you can safely continue to do so.

If you have difficulty avoiding these foods throughout the day, your healthcare provider may recommend changing your medication schedule—even though the manufacturer recommends taking it in the morning. Taking the medication at night means “you can easily avoid things that interfere with your thyroid medication,” says Dr. Puopolo.

There are two caveats. It’s difficult to have an empty stomach for 30 to 60 minutes prior to bedtime, and many people forget to take medication before going to sleep. That’s especially true if your routine is disrupted by a late night or vacation.

Can I take vitamins and other medications?

Certain medications interact with Synthroid. “Calcium, iron supplements, antacids, and [certain] other medicines may prevent your body from fully absorbing your thyroid medication,” says Dr. Jayani. Plan your dosage for four hours before, or four hours after your daily thyroid medication. To avoid any interactions, it’s best to take Synthroid completely by itself. Consult with your healthcare provider or pharmacist about your daily schedule and if any medications you take interact with Synthroid.

The bottom line

For thyroid medication, the 30 to 60 minute wait applies to everything except a tall glass of water. Take it alone on an empty stomach. Then, avoid other medications that interfere with absorption for at least four hours, if possible. Failure to do so may mean that you are not properly medicating your thyroid condition. Even if you want that cup of joe with a splash of soy milk and a cup of OJ first thing in the morning, you may need to hold off for the sake of your overall health. Ask your healthcare provider or pharmacist for help finding a dosing plan that works for you.