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Synthroid (levothyroxine sodium) is a synthetic thyroid hormone used to treat hypothyroidism, a condition in which the thyroid gland does not produce enough thyroxine (T4). Adequate levels of thyroid hormone are critical for maintaining metabolic stability, cardiovascular function, temperature regulation, and growth and development in children. Synthroid is also used in conjunction with surgery and radioactive iodine therapy for the management of certain types of thyroid cancer.
Levothyroxine is bioidentical to endogenous thyroxine and works by restoring hormone balance in individuals with underactive thyroid function. Once absorbed, it is converted in peripheral tissues to triiodothyronine (T3), the active form of thyroid hormone, and exerts its effects on metabolism, protein synthesis, and energy regulation throughout the body.
Key Takeaways
Availability: Synthroid (levothyroxine sodium) is available by prescription through licensed online pharmacies including PlanetDrugsDirect, DrugMart, and Amazon Pharmacy. PlanetDrugsDirect offers the lowest cost Synthroid (levothyroxine sodium) at $38.99 (adjusted price for 30-tablet quantity). To purchase directly from PlanetDrugsDirect go here.
How It Works: Synthroid provides a synthetic form of the thyroid hormone T4, which regulates metabolism and supports normal growth and development. It is used to normalize thyroid hormone levels in patients with hypothyroidism or after thyroidectomy for cancer or goiter.
Common Side Effects: Frequently reported side effects include headache, leg cramps, insomnia, heat intolerance, increased appetite, weight loss, nervousness, and menstrual irregularities. Serious risks may include chest pain, palpitations, and symptoms of overtreatment such as hyperthyroidism. Seek medical attention if you experience chest pain, rapid heartbeat, or signs of hormone overdose.
4 Places to Buy Synthroid (Levothyroxine) Online
Synthroid (levothyroxine sodium) is a brand-name thyroid hormone replacement used to treat hypothyroidism, a condition in which the thyroid gland does not produce enough hormone. Synthroid provides a synthetic form of thyroxine (T4), a hormone normally produced by the thyroid to regulate metabolism, energy levels, and overall endocrine balance.
It is typically taken once daily, preferably in the morning, on an empty stomach, at least 30 to 60 minutes before eating or taking other medications. Dosages vary based on age, weight, clinical condition, and lab values, with strengths ranging from 25 mcg to 300 mcg per tablet.
Provider | Price | Prescription Required | Consultation Required | Same-Day Prescription | Link |
PlanetDrugsDirect | $38.99 for 30 tablets (300 mcg) | Yes | No | No | |
DrugMart | $36.03 for 30 tablets (300 mcg) | Yes | No | No | |
Amazon Pharmacy | $51.90 for 30 tablets (100 mcg) | Yes | No | No | |
HealthWarehouse.com | $78.00 for 30 tablets (300mcg) | Yes | No | No |
Prices updated as of April 5, 2025. Availability and costs may vary based on location, dosage strength, and provider-specific policies.
Where to Buy Synthroid (Levothyroxine) Online
Here’s where you can order Synthroid online from reputable providers:
1. PlanetDrugsDirect
PlanetDrugsDirect offers brand-name Synthroid at competitive prices and international shipping.
Price: $38.99 for 30 tablets (300 mcg)
Prescription Required: Yes
Consultation Required: No
Same-Day Prescription: No
2. DrugMart
DrugMart provides affordable monthly supplies of Synthroid with a simple ordering process.
Price: $36.03 for 30 tablets (300 mcg)
Prescription Required: Yes
Consultation Required: No
Same-Day Prescription: No
3. Amazon Pharmacy
Amazon Pharmacy offers a convenient option for a 30-tablet supply of Synthroid with home delivery and automatic refills.
Price: $51.90 for 30 tablets (100 mcg)
Prescription Required: Yes
Consultation Required: No
Same-Day Prescription: No
4. HealthWarehouse.com
HealthWarehouse.com offers a U.S.-licensed and accredited option for purchasing brand-name Synthroid (300 mcg) with reliable shipping and pharmacy support.
Price: $78.00 for 30 tablets (300 mcg)
Prescription Required: Yes
Consultation Required: No
Same-Day Prescription: No
What is Synthroid (Levothyroxine Sodium)?
Synthroid is a synthetic form of thyroxine (T4), a hormone normally produced by the thyroid gland. It is prescribed for the treatment of hypothyroidism—a condition where the thyroid does not produce sufficient hormones to meet the body’s needs. Synthroid restores adequate hormone levels to normalize metabolism, energy production, and overall endocrine function.
Synthroid is also indicated as part of the treatment protocol for certain types of thyroid cancer, particularly well-differentiated thyroid cancer, in combination with surgery and radioiodine therapy.
This medication is classified as a thyroid hormone replacement and is considered bioequivalent to naturally occurring T4. It should be used in conjunction with regular monitoring of thyroid hormone levels and is typically taken once daily on an empty stomach, 30 to 60 minutes before breakfast.
Warnings and Precautions
You should not use Synthroid if you:
Have untreated adrenal insufficiency
Have a thyroid condition called thyrotoxicosis
Recently experienced a heart attack or have active cardiac symptoms
Tell your doctor before using Synthroid if you have or have ever had:
A thyroid nodule
Heart disease, including history of stroke, arrhythmias, or blood clots
Diabetes (dosage adjustments may be needed)
Anemia
Osteoporosis or low bone mineral density
Pituitary gland dysfunction
Kidney disease
Recent radioactive iodine therapy
Food or drug allergies
Plans for surgery
Pregnancy and Breastfeeding
Pregnancy: Continue Synthroid if you become pregnant. Stopping treatment can harm both mother and fetus. Your dosage may need adjustment during pregnancy.
Breastfeeding: Synthroid is generally considered safe while nursing, but hormone levels and dosing should be monitored.
How to Take Synthroid (Levothyroxine Sodium)
Take Synthroid once daily, ideally in the morning on an empty stomach, at least 30 to 60 minutes before eating or taking other medications.
Swallow tablets whole with a full glass of water.
For infants and small children, the tablet can be crushed and mixed with a small amount of water and administered immediately by spoon or dropper. Do not store mixtures or combine with foods like soy formula, which may interfere with absorption.
Take at the same time every day to maintain steady hormone levels.
Regular blood tests (TSH, T4) are necessary to ensure proper dosage and monitor therapy.
Dosing Information
Doses are individualized based on age, weight, lab results, and underlying conditions.
Initial adult dose for hypothyroidism: 25 to 50 mcg daily, adjusted every 6–8 weeks
Maintenance dose: Typically 1.6 mcg/kg/day for full replacement in adults
Pediatric doses are based on weight and age; frequent dose adjustments are needed as the child grows
Patients may require lifelong treatment
What to Avoid
Do not use Synthroid for weight loss. High doses can cause serious or life-threatening side effects, especially when combined with appetite suppressants.
Avoid grapefruit juice, soybean flour, walnuts, cottonseed meal, and high-fiber foods around the time of dosing, as they may interfere with absorption.
Avoid taking antacids, calcium, iron supplements, and cholesterol binders within 4 hours of taking Synthroid.
Missed Dose or Overdose
Missed Dose: Take as soon as remembered. Skip if it’s close to the next dose. Do not double up.
Overdose: Call Poison Control (1-800-222-1222) or seek emergency care. Symptoms may include:
Tremors, chest pain, shortness of breath
Rapid heartbeat
Muscle cramps, nervousness
Insomnia, sweating, heat intolerance
Side Effects of Synthroid
Common Side Effects:
Headache, leg cramps, or muscle pain
Feeling nervous or irritable
Palpitations or irregular heartbeat
Weight loss or increased appetite
Heat sensitivity or sweating
Diarrhea
Menstrual changes
Partial hair loss
Serious Side Effects (Call your doctor immediately):
Chest pain or signs of a heart attack
Shortness of breath
Fever, tremors, or heat intolerance
Severe fatigue or weakness
Vomiting, diarrhea, or mood changes
Allergic Reactions: Seek emergency help if you experience hives, swelling, or trouble breathing.
Report serious side effects to the FDA at 1-800-FDA-1088.
Drug Interactions
Many medications can interfere with Synthroid’s effectiveness or absorption. Important interactions include the following.
Avoid taking these within 4 hours of Synthroid:
Calcium carbonate (e.g., Tums, Caltrate)
Iron supplements (e.g., ferrous sulfate)
Antacids with aluminum or magnesium (e.g., Maalox, Mylanta)
Cholestyramine, colestipol, colesevelam
Sucralfate
Proton pump inhibitors and H2 blockers (e.g., omeprazole, lansoprazole)
Always tell your healthcare provider about all medications and supplements, including over-the-counter products and vitamins.
Storage
Store at room temperature (68°F to 77°F or 20°C to 25°C)
Keep in original container, away from moisture and heat
Keep out of reach of children
Rely on PlanetDrugsDirect.com to Buy Online Synthroid (levothryroxine sodium)
As a trusted prescription referral service, we offer important benefits whenever you order online. Each of our partner pharmacies and/or government-approved dispensaries is committed to providing the best experience possible of any online prescription referral service on the internet. We offer:
Low prices
Quick turn-around times
Generic and brand-name medications
Unparalleled customer service
Sources
U.S. Food and Drug Administration. (2017). Synthroid (levothyroxine sodium) tablets, for oral use: Prescribing information. Retrieved from https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/021402s024s028lbl.pdf
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