Levothyroxine

Synthroid, Levoxyl, Tirosint, Thyro-Tabs, ThyroKare, Euthyrox, Levo-T, Thyquidity, Ermeza, Thyrocryn, Unithroid, Thyrolar

Thyroid hormone • Synthetic T4

Premium

NTI

Half-life

6-7 days

Protein Binding

>99%

Metabolized By

N/A

External

Drugs.com

Boxed warning

Should not be used for weight loss — doses within or above normal range are ineffective and potentially toxic

Clinical alerts

Boxed warning

1 boxed warning

Narrow therapeutic index

Small dose changes can cause toxicity or loss of effect

Mechanism of action

Synthetic thyroxine (T4) that is converted to active T3, regulating metabolism

Recorded indications

From the drug index — may include conditions studied rather than approved indications

·Hypothyroidism
·Congenital Hypothyroidism
·Febrile Convulsion
·Neuroendocrine Stress Response
·Fever

Interactions

1 curated · 0 major or contraindicated · select a row for management

Interacting drug	Severity	Effect
rifampicin	moderate	Decreased levothyroxine levels; hypothyroidism may develop or worsen.

Common adverse effects

Palpitations
Tachycardia
Weight loss
Tremor
Insomnia

Food, alcohol & herbal

Food

Take on empty stomach 30-60 min before breakfast
Calcium, iron, and fiber reduce absorption

Alcohol · minor

No significant interaction

Herbal

Soy (moderate) — May reduce absorption

Pharmacokinetics

Half-life: 6-7 days
Protein binding: >99%

Pregnancy & lactation

Not recorded for Levothyroxine. Absence here means this database does not hold a category — not that the drug is safe in pregnancy or breastfeeding.

Sources

Assembled from: drug index, curated drug database, curated interaction pairs.

Not a substitute for clinical judgement

Levothyroxine

Synthroid, Levoxyl, Tirosint, Thyro-Tabs, ThyroKare, Euthyrox, Levo-T, Thyquidity, Ermeza, Thyrocryn, Unithroid, Thyrolar

Thyroid hormone • Synthetic T4

Premium

NTI

Half-life

6-7 days

Protein Binding

>99%

Metabolized By

N/A

External

Drugs.com

Boxed warning

Should not be used for weight loss — doses within or above normal range are ineffective and potentially toxic

Clinical alerts

Boxed warning

1 boxed warning

Narrow therapeutic index

Small dose changes can cause toxicity or loss of effect

Mechanism of action

Synthetic thyroxine (T4) that is converted to active T3, regulating metabolism

Recorded indications

From the drug index — may include conditions studied rather than approved indications

·Hypothyroidism
·Congenital Hypothyroidism
·Febrile Convulsion
·Neuroendocrine Stress Response
·Fever

Interactions

1 curated · 0 major or contraindicated · select a row for management

Interacting drug	Severity	Effect
rifampicin	moderate	Decreased levothyroxine levels; hypothyroidism may develop or worsen.

Common adverse effects

Palpitations
Tachycardia
Weight loss
Tremor
Insomnia

Food, alcohol & herbal

Food

Take on empty stomach 30-60 min before breakfast
Calcium, iron, and fiber reduce absorption

Alcohol · minor

No significant interaction

Herbal

Soy (moderate) — May reduce absorption

Pharmacokinetics

Half-life: 6-7 days
Protein binding: >99%

Pregnancy & lactation

Not recorded for Levothyroxine. Absence here means this database does not hold a category — not that the drug is safe in pregnancy or breastfeeding.

Sources

Assembled from: drug index, curated drug database, curated interaction pairs.

Not a substitute for clinical judgement

Levothyroxine Drug Profile | PharmaGraphX