Levothyroxine

Hypothyroidism (underactive thyroid), whether from Hashimoto’s thyroiditis, thyroid surgery, radioiodine treatment, or other causes. Also used for TSH suppression after thyroid cancer.

Levothyroxine is synthetic T4 (thyroxine), identical to what your thyroid gland normally produces. Once absorbed, it’s converted to T3 (the active hormone) in your tissues, restoring normal thyroid hormone levels throughout the body. This normalises metabolic rate, energy, weight, mood and temperature regulation.

Anyone with hypothyroidism. Dose is adjusted based on blood TSH levels. Start low and increase gradually, especially in elderly patients or those with heart disease. Suitable in pregnancy (dose often needs increasing).

Order online and we review your request. A prescriber checks your consultation form for clinical appropriateness and contacts you if anything else is needed. Once approved, your medication is dispensed and delivered to your door.

Tracked: Tracked delivery, arrives in two working days - Free

When it arrives: Every order is sent tracked. Where this page says in post today, it goes out today. Where it says in post tomorrow, it goes out the next working day. On the rare occasions a medicine is unavailable, we will contact you to talk about timing and alternatives.

We dispense clinically equivalent generic medications where available. Prices shown are for the generic version. If you prefer the branded version, let us know in your order form and we will confirm any price difference.

Levothyroxine from £20.99 per pack.

When correctly dosed, side effects are uncommon. Signs of overdose (dose too high): palpitations, tremor, weight loss, anxiety, diarrhoea, heat intolerance. Signs of underdose: fatigue, weight gain, constipation, cold intolerance.

Thyrotoxicosis (unless as part of block-and-replace). Use with caution in cardiovascular disease, adrenal insufficiency (correct before starting).

Calcium, iron, and antacids: take 4 hours apart (reduce absorption). Warfarin: levothyroxine increases anticoagulant effect. Absorption affected by many drugs - take consistently on an empty stomach.

Levothyroxine: safe and essential in pregnancy - dose usually needs increasing. Carbimazole: avoid in 1st trimester if possible (risk of aplasia cutis) - propylthiouracil preferred. Both require close specialist monitoring.

Take on an empty stomach, 30-60 minutes before breakfast (or at bedtime, 2 hours after food). Consistency is key - take at the same time daily. Many medications and supplements interfere with absorption (iron, calcium, PPI) - separate by at least 4 hours. Blood tests needed 6-8 weeks after any dose change. Don’t switch brands without retesting - bioavailability can differ.