Thyroid ConditionsLong-term condition

Hypothyroidism

Also called: underactive thyroid, low thyroid, Hashimoto's thyroiditis

An underactive thyroid gland that does not make enough thyroid hormone, slowing many of the body's processes. Treated with a daily hormone replacement tablet.

Quick answer

What it is: The thyroid gland in the neck produces hormones that set the pace of metabolism. In hypothyroidism it does not produce enough, and body processes slow down.
Common symptoms: Tiredness, feeling cold, weight gain, dry skin, constipation, low mood and heavier or irregular periods are common — all of which have many other causes.
How it's treated: A daily levothyroxine tablet that replaces the missing hormone, with the dose adjusted based on blood TSH levels.
Who can help: Diagnosis and dose adjustments come from a physician or nurse practitioner using blood tests. Pharmacists help with timing, absorption and interactions.
Warning signs: Chest pain or a racing, irregular heartbeat on treatment needs prompt assessment — it can indicate the dose is too high.

Managing this long term? Pill4Me pharmacists in Chilliwack can help.

Book a medication review

What is hypothyroidism?

The thyroid produces thyroxine (T4), which the body converts to the active form (T3). These hormones influence heart rate, body temperature, digestion, mood, skin, hair and how quickly you burn energy. When production falls, everything runs slightly slow — which is why the symptoms are so wide-ranging and so easily attributed to something else.

The most common cause in Canada is Hashimoto's thyroiditis, where the immune system gradually damages the thyroid. It can also follow thyroid surgery, radioactive iodine treatment, or certain medications. Diagnosis is made on bloodwork rather than symptoms: a raised TSH means the pituitary is pushing a thyroid that is not responding adequately.

Treatment replaces what the gland is not making, and it works well — but it is precise. Levothyroxine has a narrow therapeutic range, which means small changes in how much you absorb can shift your results out of target. That is why the advice about timing, food and supplements matters more here than with most medications.

Common symptoms

Symptoms develop slowly and are easy to miss. They can include:

Tiredness that does not improve with rest
Feeling cold when others do not
Weight gain despite no change in eating
Dry skin and brittle hair or nails
Constipation
Low mood, or difficulty concentrating
Heavier or irregular menstrual periods
Muscle aches, cramps or weakness
A hoarse voice or puffiness around the face

Having these symptoms does not confirm a diagnosis — they overlap with other conditions. Assessment by a pharmacist, physician or nurse practitioner is what establishes the cause.

Causes and risk factors

What causes it

Hashimoto's thyroiditis — an autoimmune process that gradually reduces thyroid function, and the most common cause in Canada
Surgical removal of part or all of the thyroid
Radioactive iodine treatment for an overactive thyroid
Certain medications, including amiodarone and lithium
Thyroid inflammation after pregnancy, which is sometimes temporary

What raises the risk of developing it

Being female — hypothyroidism is substantially more common in women
Age, with risk rising over 60
A family history of thyroid or autoimmune disease
Another autoimmune condition, such as type 1 diabetes or celiac disease
Previous thyroid surgery or radiation to the neck
The first year after giving birth

Risk factors make a condition more likely across a population — they are not causes, and having several does not mean you will develop it.

When should I seek medical care?

Seek urgent or emergency care

Chest pain, or a rapid or irregular heartbeat
Severe shortness of breath
Extreme drowsiness, confusion or very low body temperature in someone with untreated or severely undertreated hypothyroidism — this is rare but a medical emergency

If you are unsure how urgent something is, call 8-1-1 to speak with a HealthLink BC nurse at any hour, or 911 in an emergency.

Worth asking a pharmacist

Timing — when to take levothyroxine relative to breakfast, coffee and other medications
Calcium, iron or antacids in your routine, all of which block absorption if taken too close together
A switch between brands or manufacturers at refill, which is worth flagging
Missed doses, or a routine that is difficult to keep consistent
Whether a new over-the-counter product or supplement affects your thyroid medication

See a physician or nurse practitioner

Symptoms persisting despite treatment, or returning after being stable
TSH results outside your target range
Pregnancy or planning a pregnancy — thyroid requirements usually rise and need earlier, closer monitoring
New swelling or a lump in the neck
Symptoms of an overactive thyroid on treatment: palpitations, feeling wired, unexplained weight loss, heat intolerance

How is hypothyroidism treated?

Lifestyle measures

Consistency matters more than diet — take the tablet the same way every day
Separate calcium and iron supplements from levothyroxine by at least four hours
High-fibre foods and coffee close to the dose reduce absorption noticeably
There is no evidence that a specific diet treats hypothyroidism, and iodine supplements are not recommended without medical advice

Medication

Levothyroxine is a synthetic form of T4 and is the standard treatment. It is taken once daily on an empty stomach, usually 30 to 60 minutes before breakfast, though bedtime dosing works well for some people as long as it is consistent. The dose is individual and is adjusted based on TSH results rather than symptoms alone. Combination T4/T3 products and desiccated thyroid extract are not routinely recommended in Canadian practice.

Monitoring

TSH is usually rechecked six to eight weeks after starting or changing a dose, since the effect takes that long to settle, then periodically once stable. It is also rechecked after switching manufacturer, during pregnancy, and when a new medication that affects absorption is started.

This is a general overview, not a treatment plan. What is right for you depends on your history, your other conditions and everything else you take — that is a conversation with your prescriber or pharmacist.

Medications used for hypothyroidism

These are commonly used in Canada for this condition. Being listed here does not mean a medication is appropriate for you — that depends on your assessment.

Synthroid

levothyroxine sodium

Daily thyroid hormone replacement for an underactive thyroid — timing and consistency matter more than with most medications.

Browse every guide in the Drug Information A–Z.

Can a BC pharmacist assess hypothyroidism?

Not for diagnosis

Hypothyroidism is diagnosed and dosed by a physician or nurse practitioner based on blood tests, and is not one of the minor ailments BC pharmacists can diagnose. Where pharmacists make a practical difference is absorption: timing relative to food and coffee, separating calcium and iron, flagging a manufacturer change at refill, and catching interactions with new medications. Those details are the difference between a stable TSH and an unexplained one.

Coverage in British Columbia

Levothyroxine is inexpensive and widely covered, subject to your PharmaCare plan and deductible. Because it has a narrow therapeutic range, staying on the same product consistently matters — if a substitution would be made at refill, we will flag it with you and your prescriber rather than switching quietly. Call 604-705-3644 to check your coverage.

Coverage depends on the medication, indication, PharmaCare plan and, for some medications, Special Authority requirements — see BC PharmaCare.

Frequently asked questions

What are the symptoms of an underactive thyroid?

Tiredness, feeling cold, weight gain, dry skin, constipation, low mood, and heavier or irregular periods are the most commonly reported. Every one of those has other explanations, which is why hypothyroidism is diagnosed on bloodwork rather than on symptoms. If several of them have crept up over months, a TSH test is a reasonable thing to ask your prescriber about.

Why does levothyroxine have to be taken on an empty stomach?

Food substantially reduces how much you absorb — high-fibre foods and coffee in particular. Taking it 30 to 60 minutes before breakfast with water gives you the full dose. If mornings are difficult, bedtime dosing at least three hours after eating works well for many people. What matters most is doing it the same way every day, because your dose was set based on how much you were absorbing.

Can I switch between Synthroid and a generic levothyroxine?

It is generally better to stay on the same product. Small differences in potency between manufacturers can shift your TSH outside target, which matters more with levothyroxine than with most medications because its therapeutic range is narrow. If a switch does happen, ask your prescriber to recheck your TSH six to eight weeks later. We flag manufacturer changes at refill rather than substituting silently.

Can a pharmacist treat hypothyroidism in BC?

Not diagnose it — thyroid conditions are not among the minor ailments BC pharmacists can assess and prescribe for, and diagnosis requires blood tests. Pharmacists can renew existing prescriptions in certain circumstances, and they are the right people to ask about timing, absorption, supplement interactions and manufacturer changes. If you need testing or a dose change, that is a physician or nurse practitioner conversation.

Will I need levothyroxine for life?

Usually yes, when hypothyroidism is permanent — which it is in Hashimoto's and after thyroid surgery or radioactive iodine. Some cases, such as thyroid inflammation after pregnancy or certain medication-induced cases, are temporary and treatment can be stopped under supervision with monitoring. Your prescriber decides based on the cause and on repeat testing.

Related conditions

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Guides and services

How BC PharmaCare coverage works

Managing this long term?

Most of what goes wrong with long-term conditions is medication-related — interactions, side effects that quietly stop people taking things, doses that drift out of step. A pharmacist review covers all of it, and moving your prescriptions to Pill4Me means someone is watching Hypothyroidism between appointments.

Book a medication review Transfer my prescription Request a refill

Pill4Me Pharmacy is at 5625 Promontory Rd Unit 101, Chilliwack, BC. We deliver free to Chilliwack, Sardis, Promontory, Vedder and Yarrow, and you can reach a pharmacist directly at 604-705-3644.