GLP-1 and Hashimoto's: What UK Adults Need to Know (October 2026)

01 · The core answer

Can you take a GLP-1 medicine if you have Hashimoto's?

You may be able to, but the answer is individual and belongs to a prescriber, not a web page.

Mounjaro (tirzepatide) is a once-weekly injectable prescription medicine licensed in the UK for weight management in adults and for type 2 diabetes.¹ It is supplied only after an online consultation reviewed by a GPhC-registered prescriber, and it is used alongside a reduced-calorie diet and increased physical activity.¹ Your thyroid condition, and the medicine you take for it, are exactly the kind of detail that review exists to weigh up.

02 · Your next step

What decision are you actually facing?

For most people with Hashimoto's, the real question is whether weight management treatment is worth exploring now. The sensible order is to make sure your thyroid care is steady, then have a weight-management conversation with a prescriber who knows about it.

Steady usually means your levothyroxine dose has been settled and your latest blood results have been reviewed by your own GP or specialist. The prescriber reviewing a Mounjaro consultation will want to see that picture.

If you are ready to look further, you can read about our weight loss clinic, or see current prices and start a free consultation on the Mounjaro pen page.

Related guide: Do glp1 help with adhd.

Related guides: Hashimoto's and mounjaro and Does glp1 help endometriosis.

03 · How Mounjaro works

How Mounjaro works, and why that matters for you

Mounjaro contains tirzepatide, which activates two natural gut-hormone receptors at once: GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin.¹ In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.

This is a gut-hormone and appetite pathway. It is a different system from the thyroid, and Mounjaro is not a thyroid treatment. That is why it never replaces levothyroxine or any other thyroid care your clinician has arranged.

It comes as a pre-filled multi-dose pen, the KwikPen, in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹ The dose is stepped up gradually, with at least 4 weeks on each dose depending on how you respond, and your prescriber guides each step. Our explainer on how GLP-1 medicines help weight loss goes deeper on appetite and fullness.

04 · Levothyroxine and timing

Taking levothyroxine alongside Mounjaro

If you take levothyroxine, tell the prescriber so it is recorded in your consultation.

Mounjaro slows how quickly the stomach empties.¹ Because other tablets pass through the same stomach, it is reasonable to ask your prescriber or pharmacist whether anything about when you take your morning tablet should change. Read the patient information leaflet for your pen and the leaflet that came with your levothyroxine, and do not alter your thyroid dose on your own.¹³

Your levothyroxine dose is set from your own blood tests by your own clinician. If your weight changes substantially during treatment, mention it at your next thyroid review so the people managing your dose have the full picture.

05 · Thyroid symptoms and side effects

Hyperthyroidism, new symptoms and Yellow Card

Hyperthyroidism is not a listed side effect of Mounjaro in the SmPC or the patient information leaflet.¹¹³

That said, Hashimoto's can itself shift over time. Thyroid levels in people with the condition can change for reasons unrelated to any injection. If you notice new symptoms, such as feeling unusually wired, unusually sluggish, or a change in heart rate, do not assume the cause. If you have a racing heart or fainting, get medical help straight away. Speak to your prescriber or GP and ask whether your thyroid bloods should be checked.

You can also report a suspected side effect through the MHRA Yellow Card scheme.¹⁹

Everyday tolerability is a separate matter. Read the patient information leaflet before your first dose.¹³ Our prescribing team offers side-effect support as part of ongoing monthly reviews.

06 · Weight and an underactive thyroid

Weight gain, belly fat and an underactive thyroid

An underactive thyroid can make weight harder to manage, but it does not make weight loss impossible.

What is reasonable to say is that "Hashimoto's belly" is a popular phrase rather than a diagnosis. Weight can build up for many reasons, including appetite, activity, sleep, other medicines and how well thyroid levels are controlled. A GP can look at your thyroid control first, which is often the right starting point.

Many people with Hashimoto's do keep a healthy weight, and many struggle. Neither says anything about your character. If your thyroid is well managed and weight is still a health concern, the next question is whether a weight-management medicine is appropriate.

The headline evidence for Mounjaro comes from a trial in the general population, not a Hashimoto's population. In the SURMOUNT-1 trial of 2,539 adults, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² These are trial averages — individual results vary, and treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.²

07 · Choosing a GLP-1 option

Which GLP-1 suits Hashimoto's?

No licensed weight-loss injection is best for everyone, including people with an underactive thyroid; your prescriber decides what suits you.

The licensed options differ in practical ways. Mounjaro is a once-weekly pen with six strengths from 2.5mg to 15mg.¹ Wegovy (semaglutide) is also once weekly, with pens of 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg, stepping up after at least four weeks to the 2.4mg maintenance dose from week 17.¹⁸ Liraglutide, as in Saxenda, is a daily injection supplied at 6mg per millilitre.

The right choice depends on your health history, other medicines, goals and what you tolerate. A prescriber is better placed to weigh that up than a general guide. You can look at the Wegovy pen alongside Mounjaro and discuss the difference in your consultation.

Do not pick a medicine because of an online claim that it is better for thyroid patients.

08 · Access: NHS and private

NHS and private routes

Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition, and the NHS primary-care rollout began in June 2025 with the highest-need groups first (initially BMI 40+ with four or more qualifying conditions).⁴⁶ Full rollout is expected to take years, which is why many people who meet the licensed criteria choose regulated private treatment rather than waiting.

If you have Hashimoto's, your GP is also the right person to ask about the NHS route, because they can see your thyroid history and results.

Benefits are a different question. The NHS prescription charge in England is £9.90 per item, and your GP or pharmacist can explain whether you qualify for exemptions or a prepayment certificate.

If you choose a private route, check the pharmacy is registered. EverydayMeds is a GPhC-registered UK online pharmacy, registration 9012878, and you can verify it on the GPhC register.¹²

09 · Applying through us

How a consultation works if you have Hashimoto's

The consultation is free, and you declare your thyroid condition and medicines in a short health questionnaire. There is no charge and no obligation. A GPhC-registered prescriber then reviews your answers; this is a clinical review, not a scoring script.

Payment is taken when you place the order; if the prescriber decides the treatment is not suitable, the order is refunded automatically in full. Approved orders are dispensed by our registered pharmacy, with same-day dispatch when ordered by 3pm and free next-day tracked delivery in temperature-controlled packaging.

Supply is official LillyDirect supply: Mounjaro direct from Eli Lilly's UK distribution, genuine KwikPens, with all six doses in stock. For reference, your first 2.5mg pen costs £129.99 with code FIRST40 (standard price £169.99), and every later order is £25 off the standard price.

Aftercare includes ongoing monthly reviews, dose titration and side-effect support. Repeat orders re-check suitability, and there is no auto-shipping, which matters if your thyroid bloods or levothyroxine dose change along the way. Let the team know if they do.

10 · Questions to ask

Questions to ask before you start

Go into the consultation, or your GP appointment, with a short list. It makes the conversation more useful and keeps decisions where they belong.

• Are my thyroid levels stable enough for the dose of levothyroxine I am on, and when were they last checked?
• Does anything about my levothyroxine routine need to change when I start a medicine that slows stomach emptying?
• Which symptoms should prompt me to book a thyroid blood test during treatment?
• Does my wider history, including any family history the leaflet asks about, affect suitability?
• How will my weight changes be reported back to whoever manages my thyroid dose?
• What happens if I stop? Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system.¹

Read the patient information leaflet in full before your first dose, and keep the pen stored as instructed: in a fridge at 2–8°C until first use, then for up to 30 days (not above 30°C) out of the fridge once in use.¹³

Mounjaro (tirzepatide) is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. It is used alongside a reduced-calorie diet and increased physical activity. Individual results vary. This page is information, not a substitute for medical advice.

11 · Serious side effects

Serious side effects: when to get help straight away

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for: severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis); pain in the upper right abdomen, fever or yellowing of skin/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹