Hypothyroidism can make you feel tired, cold, foggy or low-energy. That’s because your thyroid makes certain hormones and with hypothyroidism, your body doesn’t make enough of them.
Levothyroxine is a medication that can replace the missing hormones. It’s the most common treatment for hypothyroidism and it can help improve your energy and metabolism so you feel better.
Paul Thompson, a pharmacist with Banner Pharmacy Services, explained more about how levothyroxine works, how to take it and what to expect.
What levothyroxine does
Levothyroxine is a substitute for one of the thyroid hormones your body normally makes, called thyroxine or T4. It brings your hormone levels back into balance, so your body can work the way it should. It helps with your:
- Energy levels
- Metabolism
- Body temperature
- Digestion
- Brain function
- Mood
How to take levothyroxine correctly
“Levothyroxine works best when it’s absorbed consistently, which is why how and when you take it matters,” Dr. Thompson said.
Take levothyroxine on an empty stomach
Food can reduce absorption. You can take it first thing in the morning with plain water and wait 30 to 60 minutes before eating anything. Or you can take it at bedtime as long as it’s been three to four hours since you’ve eaten anything.
Take levothyroxine at the same time every day
Taking levothyroxine at the same time and under the same conditions helps keep your hormone levels steady and builds a consistent routine. Even a small change in timing can have an impact.
Be careful with coffee and supplements
Coffee and supplements can interfere with how much medication your body absorbs.
- Wait 30 minutes after taking levothyroxine before drinking coffee
- Don’t take calcium, iron, antacids or multivitamins for at least four hours after your levothyroxine dose
How long does levothyroxine take to work?
Levothyroxine doesn’t work overnight. It takes time to reach steady levels in your body:
- One to two weeks: Your blood levels begin to change, although you may not feel a difference
- Four to six weeks: You should notice improvements
- Eight to 12 weeks: You should get the full benefit
Your provider will probably check your thyroid levels after six to eight weeks and may adjust your dose based on your lab results.
Common reasons levothyroxine may not seem to work
“If levothyroxine doesn’t seem effective, it’s often not the medication itself but timing, absorption or dosing issues. The good news is it’s usually fixable,” Dr. Thompson said.
Levothyroxine may not seem to work if you:
- Take it with food or coffee
- Miss doses, which can cause shifts in your hormone levels
- Take supplements too soon after taking levothyroxine
- Have certain gastrointestinal conditions, like celiac disease, H. pylori infection or atrophic gastritis
- Take medications that interfere with absorption, like antacids, proton pump inhibitors or bile acid binders
- Need a dose adjustment due to weight changes, pregnancy or other health conditions
It may also seem like levothyroxine is not helping with hypothyroidism symptoms if you switch between brands or generics. “A common myth is that brand name Synthroid works better than generic levothyroxine. The issue is rarely the generic itself but changes between products and generic manufacturers,” Dr. Thompson said.
The reason for this is that levothyroxine is a narrow therapeutic index drug, which means even the smallest changes can affect how you absorb the medication. Switching manufacturers can lead to hormone fluctuations that some people notice more than others. Because many patients cannot control which generic manufacturer they receive from the pharmacy, your provider may recommend a brand-name medication that is marked “dispense as written” if you are having symptoms or unstable lab results. This helps keep the medication formulation consistent from refill to refill.
Whether you take brand-name or generic levothyroxine, consistency matters. Take your medication the same way each day and talk to your provider before making changes. You may also need lab testing after a medication change to make sure your thyroid levels stay in range.
Side effects to watch for
Most people tolerate levothyroxine well and side effects are generally caused by a dose that is too high or too low.
Signs your dose may be too high:
- Feeling jittery, anxious or nervous
- Sweating
- Fast or irregular heartbeat
- Shakiness or tremor
- Trouble sleeping
- Being sensitive to heat
- Unexplained weight loss
Doses that are too high may increase the risk of bone loss or heart rhythm problems, particularly in older people.
Levothyroxine should never be used for weight loss in people who have normal thyroid function.
Signs your dose may be too low:
- Ongoing fatigue
- Feeling cold when other people are comfortable
- Brain fog or trouble concentrating
- Fatigue or low energy
- Weight gain
- Constipation
- Dry skin
- Dry, brittle hair
- Hair loss
- Depression or low mood
- Slow heart rate
- Heavy or irregular menstrual periods
When to talk to your health care provider
Talk to your provider if:
- Symptoms are not improving after six to eight weeks
- You have signs that your dose is too high or too low
- You start or stop other medications or supplements
- You are pregnant or planning pregnancy
- You switch brands or pharmacies
- You miss several doses or accidentally take too much
Your provider can check your levels and adjust your dose if needed.
Tips to get the most benefit from levothyroxine
Levothyroxine works best when you take it correctly:
- Set a daily reminder and stick to a routine, even on weekends
- Remember not to have food, coffee or supplements close to the time you take it
- Track your symptoms and share any changes with your provider
The bottom line on levothyroxine
Levothyroxine is a safe and effective treatment for hypothyroidism. You’ll need to take it for life but it can help your body function normally again. If you have questions about your thyroid medication or symptoms, a Banner Health provider can help you find the right dose and keep your thyroid levels on track.
FAQs
What is levothyroxine used for?
It treats hypothyroidism by replacing a missing thyroid hormone.
When should I take levothyroxine?
Most people find it’s best to take it in the morning on an empty stomach, 30 to 60 minutes before eating.
Can I take levothyroxine with coffee?
It’s best to wait at least 30 minutes before drinking coffee.
How long does levothyroxine take to work?
You may feel better within a few weeks but full effects can take six to eight weeks.
Why am I still tired after taking levothyroxine?
Your dose may need adjustment or absorption may be affected by timing or supplements.
Can I switch between levothyroxine brands?
You can but your provider may need to monitor your levels closely.
