When the small gland at the front of the neck slows down, everything else slows with it. Cold, tired, gaining weight, flat.
Synthroid simply supplies the hormone the gland is no longer producing enough of.
Without prescription, plain packaging. It is not a weight loss drug.
The thyroid sets the metabolic pace of the whole body. Run it slow and everything slows down.
Leaden fatigue despite sleeping enough. Feeling cold when nobody else does. Weight gain without eating differently. Dry skin, brittle hair, constipation, low mood, difficulty concentrating.
All of which gets attributed to stress, age or depression. Meanwhile a straightfoward blood test finds the cause, and it treats extremely well.
How it works
It contains levothyroxine, which is chemically identical to the hormone your thyroid produces.
So this is not a drug interfering with a process. It is straightforward replacement — supplying what the gland no longer supplies.
The body converts it to the more active form as needed, so that regulation stays intact. Which is a large part of why the treatment works as well as it does.
Used for
An underactive thyroid from various causes
After surgical removal of the thyroid
Goitre, where the gland has enlarged
After thyroid cancer surgery, to keep the controlling hormone suppressed
Is it a weight loss drug?
Needs saying plainly, because this gets attempted regularly.
In someone with a normally functioning thyroid, taking this does not produce healthy weight loss. It produces an artificial overactive state.
The consequences are palpitations, rhythm disturbances, tremor, insomnia, inner restlessness and accelerated bone loss.
And what is lost is largely muscle rather than fat. The heart pays for it.
Conversely, someone with a genuine deficiency who is correctly treated often sees their weight normalise on its own — because metabolism returns to its proper rate.
How you take it matters more than almost any other medicine
Morning, on an empty stomach, first thing.
With a glass of water, not coffee or tea.
Then nothing to eat for at least half an hour.
Same time every single day.
Missed dose: take it later the same day, otherwise skip.
Coffee is the most common obstacle, since for many people it is the first thing of the day. It measurably reduces absorption.
If that routine is impossible, an evening dose works — but several hours after the last food. Consistency matters more than which option you pick.
Keep these well apart from it
Calcium and iron supplements
Magnesium
Antacids for heartburn
Large amounts of dairy
Soy products
High-fibre supplements
All of these bind the hormone in the gut so it never gets absorbed. Leave several hours.
This is not a technicality. Swallowing the tablet alongside a calcium supplement wastes a substantial part of the dose, and the blood test then does not match the amount being taken.
Proton pump inhibitors for reflux can also affect absorption.
Why the dose is not adjusted by feel
The right amount is highly individual and the window between too little and too much is narrow.
Too little: symptoms persist. Too much: palpitations, restlessness, insomnia, weight loss, bone loss.
It is adjusted according to a blood marker, not according to how you feel on a given week. And after any change it takes several weeks before a new equilibrium is reached — measured sooner, the result means little.
Check it regularly even when things are fine. Requirements change over a lifetime, and the drift is slow enough to be invisible.
Signs of too much
Palpitations or a stumbling heartbeat
Inner restlessness, nervousness
Insomnia
Sweating and feeling hot
Tremor
Weight loss despite a good appetite
Diarrhoea
Those warrant rechecking the dose — not stopping it, and not halving it on your own.
Special situations
In pregnancy, requirements rise noticeably and often early. Deficiency at that stage matters for the baby's development, so levels need close monitoring.
In heart disease and in older people, treatment starts at a very low dose and increases slowly to avoid straining the heart.
And one practical point: do not switch between manufacturers unnecessarily. Small formulation differences can shift the result, so recheck after any change.
Ordering without prescription: how it works
This is lifelong treatment, so the only real consideration is never running out.
Pick the strength and the pack size, put in a delivery address, confirm. Couple of minutes, any time of day, no queue and no conversation across a counter.
It goes out in plain packaging. No pharmacy name on the outside, nothing that hints at what is inside. How long delivery takes depends on where the parcel is headed.
On price it comes down to strength and pack size. Larger packs generaly work out better per unit.
If something arrives damaged anywhere in the UK, send the order number and a photograph the same day. We replace free of charge or refund in pounds. Do not use medication from a damaged blister.
