ð Levothyroxine â Information for Older Adults
Plain-language information about levothyroxine in older adults. This page is for older Canadians and their caregivers. It does not replace advice from your own health-care provider.
Levothyroxine
Thyroid Hormone Replacement
1. What is levothyroxine used for?
Levothyroxine is a thyroid hormone replacement medication. It is a man-made version of T4, a hormone that your thyroid gland normally produces.
Levothyroxine is used to treat:
- Hypothyroidism â when your thyroid gland doesn't make enough hormone on its own
- After thyroid surgery â to replace hormones when some or all of the thyroid has been removed
- Certain thyroid conditions â sometimes used alongside other treatments
ðĄ Good to know
Hypothyroidism is very common in older adults, especially women. Levothyroxine has been used safely for many decades and is one of the most commonly prescribed medications in Canada. When the dose is right, most people feel much better.
A butterfly-shaped gland in your neck that controls metabolism, energy, and many body functions
Helps control energy, body temperature, heart rate, weight, and how your organs work
2. How does levothyroxine usually help?
When your thyroid doesn't make enough hormone, you can feel unwell in many ways. Levothyroxine replaces the missing hormone and can help improve:
Reduces fatigue and that "sluggish" feeling
Helps if you've been feeling cold all the time
Can improve dry skin and hair loss
May help with "brain fog," memory, and low mood
Can help relieve constipation
Helps maintain a normal heart rate
â° Be patient
It may take several weeks (often 4â6 weeks or longer) to feel the full benefit after starting or changing your dose. Your provider will recheck your blood levels after this time to see if the dose is right.
3. Why levothyroxine needs extra care in older adults
In older adults, getting the dose exactly right is very important. Too much thyroid hormone can:
- Increase the risk of a fast or irregular heartbeat (such as atrial fibrillation)
- Speed up bone loss, increasing the risk of osteoporosis and fractures
- Worsen chest pain (angina) in people with heart disease
- Cause anxiety, tremor, and trouble sleeping
ðĻââïļ Because of this, health-care providers often:
ðĄ TSH blood test
Your provider uses a blood test called TSH (thyroid-stimulating hormone) to check if your dose is right. Paradoxically, when your thyroid hormone is low, TSH goes high, and vice versa. Your provider will explain your target range.
4. How levothyroxine is usually taken
â ïļ Important
Follow your provider's instructions exactly. Taking levothyroxine the right way helps ensure your body absorbs it properly and your levels stay stable.
In general:
Most people take it first thing when they wake up
Best absorbed when your stomach is empty â just plain water, no coffee or tea yet
Wait at least 30 minutes (ideally 60) before breakfast, coffee, or other medications
Consistency helps keep your levels stable
â ïļ Foods and supplements that can interfere
These can reduce how much levothyroxine your body absorbs if taken at the same time:
- Calcium supplements or calcium-fortified foods
- Iron supplements
- Antacids (like Tums) or heartburn medications
- Soy products in large amounts
- High-fibre foods or fibre supplements
- Coffee (can reduce absorption if taken together)
Take these at least 4 hours apart from your levothyroxine, or as your provider advises.
â If you miss a dose
Take it as soon as you remember, unless it's almost time for your next dose. Some providers say you can take two doses the next day if you miss one â ask your provider or pharmacist what they recommend for you.
ðĄ Alternative timing
If morning dosing is difficult, some people take levothyroxine at bedtime (at least 3â4 hours after eating). Ask your provider if this might work for you, especially if you take many morning medications.
5. Possible side effects older adults may notice
When levothyroxine is dosed correctly, most people don't have side effects. Problems usually happen when the dose is too high (too much thyroid hormone):
Palpitations, racing heart, or feeling your heart "skip"
Nervousness, restlessness, or trembling hands
Sweating more than usual, heat intolerance
Difficulty falling or staying asleep
Losing weight without trying
More frequent or loose bowel movements
ðĄ These are signs your dose may be too high
If you notice any of these symptoms, don't stop taking levothyroxine â but do contact your provider. They may need to check your blood levels and adjust your dose.
ð Signs the dose may be too low
If your dose is too low, your hypothyroid symptoms may continue or return:
- Feeling very tired or sluggish
- Feeling cold all the time
- Constipation, dry skin, or hair loss
- Weight gain
- Feeling down or "foggy"
Tell your provider if your symptoms aren't improving after several weeks on treatment.
6. When to be extra careful with levothyroxine
Talk to your health-care provider and be extra careful if you have:
ð Drug interactions
Many medications can affect levothyroxine levels or how well it works. Always tell your provider about all medications you take, including:
- Blood thinners (like warfarin) â levothyroxine can increase their effect
- Diabetes medications â may need adjustment
- Heart medications (like digoxin)
- Antidepressants
- Seizure medications
- Estrogen or hormone replacement therapy
ð Consistency matters
Try to stay with the same brand of levothyroxine if possible. Different brands may be absorbed slightly differently. If your pharmacy switches your brand, let your provider know â they may want to recheck your levels.
7. Habits and lifestyle that may help
While levothyroxine does the main work of replacing thyroid hormone, these habits can support your overall health:
Same time every day, same way (empty stomach, wait before eating)
Regular TSH checks help ensure your dose stays right over time
Note energy levels, mood, weight, and any new symptoms to discuss with your provider
Get enough calcium and vitamin D (timed away from levothyroxine), and stay active
No special "thyroid diet" is needed, but good nutrition supports overall health
Work with your pharmacist to time other pills and supplements around levothyroxine
â Iodine note
You don't need extra iodine supplements if you're taking levothyroxine â it already provides what your body needs. Too much iodine can actually cause problems. Most Canadians get enough iodine from iodized salt and regular food.
8. When to call your doctor, nurse practitioner, or pharmacist
(Non-urgent)
Contact your health-care provider or pharmacist if:
- You have new palpitations, nervousness, or trouble sleeping
- You feel more tired and sluggish despite taking levothyroxine regularly
- You notice unexplained weight changes (gain or loss)
- Your symptoms of low thyroid are returning or not improving
- You start or stop other medications or supplements (especially calcium, iron, antacids, or heart medicines)
- Your pharmacy switches you to a different brand of levothyroxine
- You have questions about how to time levothyroxine with other pills and meals
- You're having trouble remembering to take it the right way
- You become pregnant or are planning pregnancy (dose often needs to increase)
9. When to call 911 or go to the emergency department
ðĻ Call 911 immediately if:
- You have chest pain or pressure that does not go away
- You have a very fast or irregular heartbeat and feel unwell
- You have sudden shortness of breath
- You feel like you might faint or lose consciousness
- You have signs of a severe allergic reaction (rare): hives, swelling of face/throat, difficulty breathing
If possible, do not drive yourself. Ask someone to call for you or call an ambulance.
ð Rare but serious: Myxedema coma
In very rare cases, severe untreated hypothyroidism can lead to a life-threatening condition called myxedema coma. Signs include extreme drowsiness, confusion, very low body temperature, and slow breathing. This is a medical emergency â call 911.
10. Questions to ask your doctor or nurse practitioner
You can print these questions and bring them to your next appointment:
â ïļ Important Disclaimer
The information on SeniorHealthGuide.ca is general and may not fit your exact situation. It is for education only.
It does not replace medical advice, diagnosis, or treatment. Only a health professional who knows your medical history can tell you what is right for you.
Never start, stop, or change any medication, or make major changes to your diet, without checking with your doctor, nurse practitioner, or pharmacist.