Does Levothyroxine Cause Tinnitus?

Levothyroxine is not known as a common cause of tinnitus, and ringing in the ears is not among the side effects listed in standard patient drug information. The bigger question is usually your thyroid level: a dose that runs too high can make your heart race and your pulse "loud" in your ears, and an underactive thyroid has its own possible links to hearing changes.

So if your ears started ringing after you began levothyroxine or changed your dose, don't stop the medicine. Instead, gather a few details and ask your prescriber whether a blood test makes sense.

What levothyroxine does in your body

Levothyroxine is a man-made version of thyroxine (T4), the main hormone your thyroid gland makes. It is prescribed when the thyroid is underactive (hypothyroidism) and sometimes after thyroid surgery or as part of care for thyroid cancer.

Thyroid hormone sets the pace for many systems at once: heart rate, body temperature, energy, digestion and more. That is why the goal is a "just right" level. Your prescriber adjusts the dose based on blood tests, mainly TSH (thyroid-stimulating hormone), and on how you feel.

Because the medicine replaces a hormone your body needs, it is usually taken long term. Problems tend to come from the dose being off, not from the hormone itself.

Is tinnitus a known side effect?

The patient drug information on MedlinePlus lists effects such as weight changes, headache, diarrhea, heat sensitivity, hair loss and changes in menstrual periods. Ringing in the ears is not on that list.

That said, people do report tinnitus while taking thyroid medicine. When that happens, there are three main possibilities worth sorting out:

• The dose is too high. Too much thyroid hormone acts like an overactive thyroid. It can bring a fast or pounding heartbeat, shakiness, anxiety, poor sleep and feeling hot. A faster, stronger heartbeat can make some people hear their pulse.
• The thyroid level is still too low. Some research has linked hypothyroidism with hearing changes and tinnitus. If your dose is not yet high enough, the ringing may belong to the condition, not the pill.
• It is a coincidence. Tinnitus is very common. Noise exposure, earwax, age-related hearing changes, stress, and other medicines can all play a role, and a new symptom can simply happen to line up with a new prescription.

Ringing versus pulsing

Pay attention to what the sound is like. A steady hiss, ring or buzz is the usual type of tinnitus. A rhythmic whoosh or thump that matches your heartbeat is called pulsatile tinnitus. Cleveland Clinic lists an overactive thyroid (hyperthyroidism) among the causes of pulsatile tinnitus, which is one reason a dose that is too high deserves a look. Pulsing sounds should always be checked by a doctor, whatever you think the cause is.

Too high, too low, or just right: a quick comparison

This table shows common signs of each situation. It is a starting point for a conversation with your prescriber, not a way to adjust your own dose.

Things that can quietly shift your thyroid level

Even when your prescribed dose stays the same, the amount your body absorbs can change. That can push you higher or lower without you noticing at first. Common reasons include:

• Timing with food. Levothyroxine is usually taken on an empty stomach, 30 to 60 minutes before breakfast. Taking it with a meal one week and on an empty stomach the next can change how much you absorb.
• Calcium and iron. MedlinePlus advises taking calcium carbonate or iron supplements at least 4 hours before or after levothyroxine. Many multivitamins contain both.
• Some foods. Soy, walnuts and high-fiber foods may affect absorption. Coffee taken right with the pill may too. Grapefruit is worth asking about.
• Other medicines. Some acid reducers, cholesterol-binding drugs and other prescriptions can interfere. Your pharmacist can check your list.
• A change in tablets. If the pharmacy switched the maker of your levothyroxine, the new tablets may act slightly differently for some people.
• Weight change or pregnancy. Both can change how much hormone you need.

None of these are reasons to change anything on your own. They are useful clues to share when you call.

What the research says

The honest answer is that the evidence here is thin.

• Levothyroxine itself. There are no strong studies showing that levothyroxine, at the right dose, causes tinnitus. Reports from individual patients exist, but reports alone cannot prove cause, because so many people take this medicine and tinnitus is common.
• Low thyroid and the ear. Small studies and reviews have described links between hypothyroidism and hearing loss or tinnitus. Results are mixed, the studies are often small, and it is not clear whether correcting thyroid levels changes the ringing for most people.
• High thyroid and pulsing sounds. An overactive thyroid raises heart rate and blood flow. Medical sources list it among the possible causes of pulsatile tinnitus. This is a well-accepted connection, but it applies to the pulsing type, not every kind of ringing.

The National Institute on Deafness and Other Communication Disorders (NIDCD) notes that some medicines can cause tinnitus as a side effect, and that finding and managing an underlying cause is part of the workup. A thyroid check fits naturally into that process.

How to tell what is going on: a two-week log

Doctors can help you much faster when you bring details. For about two weeks, jot down a short note each day:

1. When you took your dose and whether you ate, drank coffee or took supplements within the next hour.
2. What the sound was like: ringing, hissing, buzzing, or a beat that matches your pulse.
3. Which ear: left, right or both.
4. How loud it seemed on a simple 0 to 10 scale, and when it was worst.
5. Other symptoms: heart racing, shakiness, poor sleep, tiredness, feeling cold or hot.
6. Your resting pulse in the morning, if you have a home blood pressure cuff or can count it for 30 seconds and double it.

Patterns often jump out. For example, a pounding pulse plus poor sleep plus ringing that is worse at night points to a different conversation than steady ringing with no other changes.

Easing the ringing while you sort it out

While you wait for test results or an appointment, a few simple, low-risk steps may make the sound easier to live with:

• Add gentle background sound. A fan, soft music or a nature-sound app can make the ringing less noticeable, especially at bedtime.
• Protect your ears from loud noise. Use earplugs for mowing, concerts or power tools so you don't add noise damage to the mix.
• Keep your morning routine steady. Same time, empty stomach, water only, and the same wait before breakfast. Consistency helps your prescriber read your blood tests accurately.
• Go easy on caffeine if you notice your heart racing. It can add to the pounding feeling when thyroid levels run high.
• Manage stress where you can. Slow breathing, a short walk or a wind-down routine won't change your thyroid, but stress tends to make tinnitus feel louder.

Your next steps

1. Keep taking your levothyroxine as prescribed and call your prescriber to report the ringing. Mention when it started and any dose or tablet changes.
2. Ask: "Could my thyroid level be off?" and "When was my last TSH test?" If it has been a while or your dose recently changed, a recheck may be reasonable.
3. Bring your two-week log and a full list of medicines and supplements, including calcium, iron and multivitamins, and ask your pharmacist about timing.
4. Ask for a hearing test if the ringing continues once your levels are in range. An audiologist can check for hearing loss, which is one of the most common partners of tinnitus.
5. Get seen quickly if the sound pulses with your heartbeat, is in one ear only, or comes with sudden hearing loss or dizziness.