thoughtscape NP Psychiatry · Patient education
Triiodothyronine-Liothyronine
Cytomel • also called T3
A thyroid hormone with two different roles: replacing low hormone or supporting depression treatment.
Draft for review · Clinical content has not been revalidated for this website.
The diagram shows thyroid-receptor activity. Depression use is separate and off-label.
What it is used for
Replaces thyroid hormone when the body does not make enough. Specialists also use it for certain thyroid tests or thyroid-cancer care.
Sometimes added when depression treatment has not helped enough. This use is off-label and does not mean your thyroid is necessarily underactive.
How it works
T3 is a hormone that helps regulate many body functions. Liothyronine is a manufactured version of it.
Its role in depression is less fully understood. More hormone does not mean more benefit; too much can strain the heart and bones.
What to expect over time
BEFORE STARTING
Agree on why you are taking it, your exact dose, thyroid tests, and follow-up plan.
FIRST WEEKS
Notice mood and daily function, but also sleep, sweating, shaking, or a racing heartbeat.
REVIEW THE BENEFIT
Depression improvement may take weeks. Thyroid replacement may be long-term; the two plans are different.
Taking your medication
Take the exact tablet strength and number prescribed, usually once daily. Doses are written in mcg, not mg.
Ask before switching thyroid medicines or adding supplements. Your dose is not interchangeable with a levothyroxine dose.
If you miss a dose, take it when remembered unless the next is nearly due. Skip it then; do not double up.
When to get help
Call 911: chest pain, collapse, major breathing trouble, or a rapid/irregular heartbeat with severe symptoms.
Call promptly: new palpitations, marked shaking, sweating, insomnia, or unusual agitation. Do not take extra doses.
Mood safety: report suicidal thoughts or much less need for sleep with risky behavior. Use 988 for crisis support; 911 for immediate danger.
Early side effects
Nervousness, trouble sleeping, sweating, feeling too hot, diarrhea, or shaking may mean the dose needs review. Temporary hair loss can occur early.
Other effects to discuss
Too much thyroid hormone over time can affect heart rhythm and weaken bones. Unplanned weight loss is not a treatment goal or a reason to raise the dose.
What to keep track of
Keep thyroid-test and follow-up appointments. Track mood, sleep, pulse symptoms, and everyday function. Feeling more wired is not the same as feeling better.
Before you start
Discuss heart disease, irregular heartbeat, diabetes, bone loss, adrenal, or pituitary problems, high thyroid levels, allergies, and bipolar symptoms. Bring every medicine and supplement you use. Tell the team about pregnancy plans or breastfeeding. Do not stop essential thyroid replacement on your own if you become pregnant; contact the prescriber promptly for a pregnancy-specific plan.
Medicines & interactions
Heart and blood-thinning medicines
Tell the team about digoxin, warfarin, and diabetes medicines. Thyroid changes can alter how much of these medicines you need.
Stimulants and psychiatric medicines
Check antidepressants, ADHD medicines, decongestants, and ketamine. Some combinations can increase heart-rate, blood-pressure, or other risks.
Absorption and supplements
Ask for a schedule if you take cholestyramine, colesevelam, or a binding resin. The label generally places T3 at least four hours before these medicines. Check supplements too.
Everyday tips
Use one written schedule and check the strength on each refill.
Bring your medicine list to appointments and tell surgical or dental teams you take T3.
Report symptoms rather than changing the dose based on how energetic you feel.
For depression, keep the rest of your treatment plan in place unless your clinician changes it.
Your questions, answered
Is this a weight-loss treatment?
No. Using thyroid hormone for weight loss can cause serious harm, especially with stimulants.
Does a normal thyroid test rule out depression use?
Not necessarily. Selected patients receive it as an add-on, with clear goals and monitoring.
Can I stop when I feel better?
Ask first. Replacement may be lifelong; a depression trial has a separate review and stopping plan.
What about pregnancy?
The preferred thyroid medicine may change. Arrange a clinician-managed plan; do not leave an underactive thyroid untreated.
Storage & safety
Keep tablets in their labeled container, away from heat, moisture, children and pets. For excess tablets, call Poison Control at 1-800-222-1222 even if you feel well; symptoms can be delayed. Call 911 for severe symptoms.
About this information
For general information only; not a substitute for individualized medical advice. This sheet does not cover every risk or interaction. Ask your prescriber or pharmacist before changing how you take this medication.
Sources
Educational inclusion does not mean this medication or its indications are treated at this practice. Review the guide for your exact product with your prescriber or pharmacist.