One in five people treated for hypothyroidism may be getting more thyroid hormone than they need. This overmedication can lead to health problems. They include arrhythmia (an irregular heartbeat), weakened bones, and mood disorders. Here's how to spot the warning signs of thyroid overmedication and what to do. Symptoms of Overtreatment Getting too much thyroid hormone may cause symptoms that mimic having an overactive thyroid (hyperthyroidism). You could experience: Heart palpitations or a faster heart rate, even at rest Trouble falling asleep Feeling jittery Sweating a lot Anxiety Shaky hands Diarrhea Weight loss Mood swings Being forgetful What to Do About Overmedication Talk to your doctor if you experience any of these symptoms. The doctor will probably check your thyroid-stimulating hormone (TSH) levels to see if your thyroid hormone dose needs adjustment. Do not change the dose on your own. It's important to have your TSH levels measured first. Only then can your doctor know whether to change your dosage. Here's how the process works. When you have hypothyroidism, the thyroid gland does not make enough thyroid hormone to meet your body’s needs. That's why you take thyroid hormone replacement therapy. A doctor prescribes a dose based on your weight, on how well your thyroid is working and on how your blood absorbs the hormone. Each person's metabolism is different and serum levels of thyroid hormone change slowly. Your doctor may need to fine-tune the dose once you start taking the medication. That's normal. When you first start treatment, your doctor will check your thyroid hormone levels about every four to eight weeks. Blood tests will show if your thyroid-stimulating hormone (TSH) is at the right level. The normal range for TSH levels is 0.3 to 4.0 mIU/L. But, your specific target range depends on your health. Finding the right dose can sometimes be a trial-and-error process. And, many things can have an effect. For instance, gaining or losing weight affects how much thyroid hormone you need. So does being pregnant. Taking medication for other health issues also can have an effect. Once you and your doctor find the right dose for you, your TSH will stay within the normal range. Then, you probably will have your next blood test in about six months and yearly after that. But, if your dose or the medication itself changes, you'll need more frequent testing again to make sure you're getting the right amount of the hormone. Now that you know the signs to watch for, remember to call your doctor right away if you experience any unusual symptoms. That's how you avoid overmedication and make sure you're taking just the right dose. Key Takeaways When you first start hypothyroidism treatment, your doctor will take frequent blood samples to check your hormone levels and see if you’re getting the right amount. Too much thyroid medication in hypothyroidism can cause health problems and trigger symptoms like the jitters, anxiety, weight loss, diarrhea and mood swings. Your thyroid hormone needs may change over time. Annual checkups to measure thyroid hormone levels are a good idea to make sure you’re always getting the correct dose—not too much or too little.