Thyronorm; Eltroxin; Synthroid (brand availability varies by market)
Dosage form
Tablet
Strength
Available in microgram strengths such as 25 mcg, 50 mcg, 75 mcg and 100 mcg; exact strengths vary.
Prescription classification
Prescription only (Schedule H / verified)
Approved routes of administration
Oral
Applies to
IN; product status and availability may vary by jurisdiction
Approved indications
A synthetic thyroid hormone used as replacement therapy for hypothyroidism. Treatment is individualized using symptoms, laboratory results, age, pregnancy status and cardiovascular history. It is not a weight-loss medicine.
Contraindications (do not use if…)
Untreated adrenal insufficiency must be addressed before treatment. Do not use after a serious hypersensitivity reaction to the formulation; product-specific contraindications must be reviewed.
Important precautions
Regular laboratory monitoring is needed because both under-replacement and excess thyroid hormone can cause harm. Heart disease, older age and changes in pregnancy status may require review. Do not change brands, strengths or schedules without advice.
Common side effects
When the dose is too high, symptoms may include palpitations, tremor, sweating, anxiety, insomnia, diarrhoea or weight loss.
Serious side effects — seek urgent medical care
Excess thyroid hormone may provoke angina, serious arrhythmias or other cardiovascular complications. Seek prompt care for chest pain, fainting or severe palpitations.
Important interactions
Calcium, iron, antacids and some cholesterol-binding medicines can reduce absorption. Proton-pump inhibitors, food timing and medicines such as warfarin or diabetes treatments may affect monitoring or response.
Allergy considerations
Check the exact formulation for inactive ingredients if a previous medicine allergy has occurred. Do not use after a serious reaction to the ingredient or excipients.
Pregnancy and lactation
Pregnancy safety
Use with caution — see notes
Notes
Thyroid hormone replacement is commonly continued in pregnancy, but requirements and monitoring often change. Contact the treating clinician promptly when pregnancy is planned or confirmed; do not stop treatment independently.
Information
Lactation safety
Use with caution — see notes
Notes
Treatment is often continued while breastfeeding when indicated. A clinician should guide monitoring and dose adjustments.
Children and older adults
Doses differ substantially by age, body size and clinical condition. Infants and older adults need careful clinician-directed selection and monitoring.
Storage
Keep tablets in their original packaging, protected from heat, light and moisture as directed by the manufacturer. Store securely away from children.
Missed dose
Follow the prescription instructions; do not take an extra dose to compensate without professional guidance, especially when several doses are missed.
Overdose
Excess amounts can cause delayed symptoms such as rapid heartbeat, tremor, agitation or chest pain. Seek urgent medical advice after an overdose.
If you suspect an overdose or accidental poisoning:
contact your local emergency services or the nearest hospital emergency department immediately. Do not wait for symptoms.
References
Medical Encyclopedia — Medical Encyclopediasource(Regulatory / approved product label (e.g. CDSCO))
RxNorm (National Library of Medicine) — RxNorm (National Library of Medicine)source(Regulatory / approved product label (e.g. CDSCO))
Thyronorm; Eltroxin; Synthroid (brand availability varies by market)
Dosage form
Tablet
Strength
Available in microgram strengths such as 25 mcg, 50 mcg, 75 mcg and 100 mcg; exact strengths vary.
Prescription classification
Prescription only (Schedule H / verified)
Approved routes of administration
Oral
Applies to
IN; product status and availability may vary by jurisdiction
Approved indications
A synthetic thyroid hormone used as replacement therapy for hypothyroidism. Treatment is individualized using symptoms, laboratory results, age, pregnancy status and cardiovascular history. It is not a weight-loss medicine.
Contraindications (do not use if…)
Untreated adrenal insufficiency must be addressed before treatment. Do not use after a serious hypersensitivity reaction to the formulation; product-specific contraindications must be reviewed.
Important precautions
Regular laboratory monitoring is needed because both under-replacement and excess thyroid hormone can cause harm. Heart disease, older age and changes in pregnancy status may require review. Do not change brands, strengths or schedules without advice.
Common side effects
When the dose is too high, symptoms may include palpitations, tremor, sweating, anxiety, insomnia, diarrhoea or weight loss.
Serious side effects — seek urgent medical care
Excess thyroid hormone may provoke angina, serious arrhythmias or other cardiovascular complications. Seek prompt care for chest pain, fainting or severe palpitations.
Important interactions
Calcium, iron, antacids and some cholesterol-binding medicines can reduce absorption. Proton-pump inhibitors, food timing and medicines such as warfarin or diabetes treatments may affect monitoring or response.
Allergy considerations
Check the exact formulation for inactive ingredients if a previous medicine allergy has occurred. Do not use after a serious reaction to the ingredient or excipients.
Pregnancy and lactation
Pregnancy safety
Use with caution — see notes
Notes
Thyroid hormone replacement is commonly continued in pregnancy, but requirements and monitoring often change. Contact the treating clinician promptly when pregnancy is planned or confirmed; do not stop treatment independently.
Information
Lactation safety
Use with caution — see notes
Notes
Treatment is often continued while breastfeeding when indicated. A clinician should guide monitoring and dose adjustments.
Children and older adults
Doses differ substantially by age, body size and clinical condition. Infants and older adults need careful clinician-directed selection and monitoring.
Storage
Keep tablets in their original packaging, protected from heat, light and moisture as directed by the manufacturer. Store securely away from children.
Missed dose
Follow the prescription instructions; do not take an extra dose to compensate without professional guidance, especially when several doses are missed.
Overdose
Excess amounts can cause delayed symptoms such as rapid heartbeat, tremor, agitation or chest pain. Seek urgent medical advice after an overdose.
If you suspect an overdose or accidental poisoning:
contact your local emergency services or the nearest hospital emergency department immediately. Do not wait for symptoms.
References
Medical Encyclopedia — Medical Encyclopediasource(Regulatory / approved product label (e.g. CDSCO))
RxNorm (National Library of Medicine) — RxNorm (National Library of Medicine)source(Regulatory / approved product label (e.g. CDSCO))
