If you are searching for GLP 1 next day delivery in the UK, Mounjaro is available through UK private prescription services and can be dispensed by GPhC registered pharmacies. Where next day delivery is offered, medicines may be sent using temperature controlled packaging. This guide is for UK adults aged 18 and over who are using or considering GLP 1 treatment and want to understand how vitamins and supplements may fit into their treatment.
If a supplement that you previously tolerated starts making you feel sick after starting Mounjaro, there may be a simple reason. Tirzepatide can slow gastric emptying, which may change how you tolerate certain foods, tablets and supplements.
This does not mean that Mounjaro has a direct interaction with vitamins. It is useful to separate a possible interaction from a change in tolerance. Some supplements may feel harder to tolerate because of their ingredients, dose or effect on the stomach.
This guide explains which vitamins and supplements may need extra care, how you may be able to take them more comfortably, how to manage side effects such as nausea, and when you may need to discuss supplements, blood tests or treatment with a healthcare professional.
Mounjaro is a Prescription Only Medicine. This information does not replace advice from your prescriber, GP or pharmacist. Tell your healthcare professional about all medicines, vitamins and supplements you take.
Key things to know
- There are no established direct drug interactions between tirzepatide and standard vitamins or minerals. However, your pharmacist or prescriber should know about all the supplements you take.
- Mounjaro can slow gastric emptying, and some supplements may be harder to tolerate if they cause nausea, stomach discomfort or constipation.
- Iron supplements can cause nausea and constipation in some people. High doses of vitamin C can also cause stomach discomfort in some people.
- Iron and calcium supplements may contribute to constipation, which can also occur as a side effect of Mounjaro.
- You do not generally need to avoid taking vitamins on your Mounjaro injection day. However, follow the instructions for each supplement and any advice from your healthcare professional.
- Taking too much of a vitamin or mineral can be harmful. Check the amount in each product before combining supplements, particularly if you take a multivitamin as well as individual vitamins or minerals.
Do Vitamins Interact With Mounjaro or Other GLP 1 Medications?
There are no established direct interactions between tirzepatide and standard vitamins or minerals. However, this does not mean that every supplement is suitable for everyone.
Mounjaro can slow gastric emptying. Because of this, some people may find that certain tablets or supplements feel harder to tolerate after starting treatment. This is different from a drug interaction.
If a supplement causes nausea, stomach pain, heartburn or constipation, speak to your pharmacist or prescriber. They may suggest changing the dose, timing or type of supplement, depending on why you are taking it.
It is also important to check whether you actually need a particular supplement. Taking more vitamins is not always better, and some vitamins and minerals can cause problems when taken in excessive amounts.
What Mounjaro Does Not Do
There are a few common claims about Mounjaro and vitamins that need some clarification.
Mounjaro can slow gastric emptying, but this is not the same as causing malabsorption. It does not work by removing the body's ability to absorb nutrients. If you have ongoing digestive symptoms or concerns about nutrient absorption, speak to your healthcare professional.
Mounjaro is also not known to make fat soluble vitamins such as vitamins A, D, E and K build up in the body simply because it slows gastric emptying. Excessive intake of these vitamins can cause problems, so follow the recommended dose and avoid combining several high dose products without professional advice.
You also do not generally need to change your vitamin schedule around your Mounjaro injection. Mounjaro is given once a week and remains in the body over time. Follow the instructions provided with your supplements and any specific advice from your healthcare professional.
What Vitamins Should Not Be Taken With Mounjaro?
No standard vitamin is automatically off limits simply because you are taking Mounjaro. However, there are a few situations where extra care is sensible.
These include taking high doses of vitamins or minerals, combining several supplements that contain the same ingredient, or using supplements that commonly cause stomach upset or constipation.
If you take prescription medicines as well as supplements, check with your pharmacist before adding a new product. They can check the full list of medicines and supplements you use and advise whether any additional precautions are needed.
Group one: anything above UK safe upper levels
| Nutrient | UK guidance on supplements | Why it matters on treatment |
|---|---|---|
| Vitamin B6 | Do not exceed 10mg a day long term unless advised | Linked to peripheral nerve damage, sometimes irreversible. Often taken for nausea without checking the amount |
| Vitamin C | Above about 1,000mg a day can cause diarrhoea and cramps | Adds to existing gastrointestinal side effects |
| Iron | Only on the basis of a blood test | Excess causes constipation, nausea and stomach pain |
| Zinc | No more than 25mg a day unless advised by a doctor | High intake causes nausea and can affect copper status |
| Vitamin D | Do not exceed 100 micrograms (4,000 IU) a day for adults | Excess causes calcium build-up over time |
| Magnesium | 400mg or less a day from supplements is unlikely to cause harm | Higher amounts cause diarrhoea |
| Vitamin A (retinol) | Avoid high doses, and avoid entirely in pregnancy | Accumulates, and is the fat-soluble vitamin most associated with toxicity |
The most common way to take too much of a vitamin or mineral is by combining several products rather than taking one product on its own. For example, a multivitamin, a separate B complex and a standalone vitamin B6 supplement may all contain the same nutrients. Check the total amount you take each day, including vitamins and minerals added to fortified drinks and protein powders.
Group Two: Supplements Worth Avoiding While on Treatment
Some supplements deserve extra caution while you are taking Mounjaro.
Products marketed as natural GLP 1 alternatives, including berberine, are one example. These products are not substitutes for prescription GLP 1 medicines. Berberine may also interact with some prescription medicines. If you are taking Mounjaro and other medicines, speak to your pharmacist or prescriber before using berberine or similar products.
Fat burners, thermogenic products and appetite suppressant blends are also best avoided unless a healthcare professional recommends them. Some contain high levels of stimulants, which may worsen nausea or cause other unwanted effects. Proprietary blends can also make it difficult to know exactly how much of each ingredient you are taking.
St John's Wort can affect how some prescription medicines work. This is not specific to Mounjaro, but you should tell your prescriber or pharmacist if you take it before starting another medicine or supplement.
Senna and other stimulant laxatives, including some herbal teas marketed for bloating or weight loss, are generally intended for short term use. If constipation continues while taking Mounjaro, speak to a pharmacist or prescriber about suitable options. Drinking enough fluid, gradually increasing fibre and, where appropriate, using a suitable laxative may help.
Group Three: Forms That May Be Harder to Tolerate
Sometimes the nutrient itself is not the main problem. The form of the supplement can also affect how well you tolerate it.
- Large tablets may feel uncomfortable if you already experience nausea or a feeling of fullness with Mounjaro.
- Effervescent and acidic products may worsen reflux or stomach discomfort in some people. Some effervescent products also contain a significant amount of sodium, so check the label.
- Iron and zinc supplements can cause stomach discomfort or nausea in some people.
- Gummy vitamins may be easier to take for some people, but they may contain added sugar and may not provide nutrients such as iron or calcium. Always check the label to see what the product actually contains.
Mounjaro and Iron Tablets
Iron is one of the supplements people often ask about when taking Mounjaro, so it is worth looking at separately.
Can You Take Iron Tablets With Mounjaro?
Yes, if iron has been recommended for you. There is no established direct interaction between iron and tirzepatide.
The main concern is that iron and Mounjaro can cause some similar side effects. Iron supplements can cause nausea, constipation, stomach discomfort and dark stools. Mounjaro can also cause nausea and constipation. Taking both may therefore make these symptoms more noticeable.
If you think you may need iron, it is better to check with your GP or another healthcare professional rather than taking a high dose supplement without a confirmed reason.
Only Take Iron Supplements If You Need Them
Iron supplements are not usually needed if you have a balanced diet and normal iron levels. If you have symptoms that could be linked to iron deficiency, such as ongoing tiredness, shortness of breath during activity, pale skin or hair thinning, speak to your GP.
A blood test can help determine whether you have an iron deficiency and whether iron supplementation is appropriate. If iron deficiency anaemia is diagnosed, your healthcare professional may also look for the underlying cause rather than simply treating the low iron level.
It is also worth remembering that tiredness can have many causes. If you are eating much less while taking Mounjaro, not getting enough calories or nutrients may also contribute to fatigue.
If Iron Has Been Prescribed and It Is Not Agreeing With You
If prescribed iron is causing side effects, speak to your prescriber or pharmacist before changing how you take it. There may be several options, depending on your individual situation.
- Taking iron with food may make it easier to tolerate, although this can reduce how much iron your body absorbs.
- Some people may be advised to take iron on alternate days rather than every day. Your prescriber can advise whether this is suitable for you.
- A different type of iron preparation or a liquid form may be easier to tolerate.
- Some forms of iron, such as iron bisglycinate, may be better tolerated by some people, although your healthcare professional can advise which preparation is appropriate for you.
Try to keep iron separate from tea, coffee, dairy products and calcium supplements because these can reduce iron absorption. Around two hours apart is commonly advised.
Vitamin C can increase iron absorption, but you do not necessarily need to take a separate vitamin C supplement with your iron. Your pharmacist or prescriber can advise whether one is needed in your situation.
One final point: intravenous iron is given by healthcare professionals in a clinical setting. It may be considered when oral iron has not worked, has not been tolerated or is not suitable. It is not something to self administer at home and is completely different from the injection used to administer Mounjaro.
Mounjaro and Vitamin C
Vitamin C is generally safe to take with Mounjaro, and there is no established direct interaction between vitamin C and tirzepatide. However, the dose and type of supplement can affect how well you tolerate it.
First, consider the amount. The UK reference intake for adults is 40mg a day, while some supplements contain 500mg or 1,000mg. Higher doses can cause diarrhoea, nausea and stomach cramps in some people. These symptoms can be particularly uncomfortable if you are already experiencing gastrointestinal side effects from Mounjaro.
The type of vitamin C may also matter. Ascorbic acid is acidic, and some people may find it worsens reflux or stomach discomfort. Effervescent products may also contain other ingredients, including sodium, so check the label before taking them regularly.
If you have a history of kidney stones or kidney problems, speak to your GP or pharmacist before taking high dose vitamin C supplements.
Can You Take Magnesium With Mounjaro?
Yes, magnesium can generally be taken with Mounjaro, as there is no established direct interaction between magnesium and tirzepatide.
However, different forms of magnesium can affect your digestion in different ways. Magnesium oxide and magnesium citrate can have a laxative effect and may cause looser stools in some people. This may be helpful if constipation is a problem, but it could make diarrhoea worse if you already have loose stools.
Magnesium glycinate may be easier to tolerate for some people who are sensitive to digestive side effects. Your pharmacist can help you choose a suitable form if you are unsure.
Magnesium is not a weight loss treatment and there is no good evidence that taking it will make Mounjaro work faster or increase weight loss.
If you have kidney disease or reduced kidney function, speak to your doctor or pharmacist before taking magnesium supplements. Your kidneys help remove excess magnesium from the body, so the appropriate dose may be different.
Vitamin D and Mounjaro
Vitamin D can be taken with Mounjaro, and there is no established direct interaction between vitamin D and tirzepatide.
UK public health guidance advises adults to consider taking a daily supplement containing 10 micrograms, or 400 IU, of vitamin D during autumn and winter. Some people may be advised to take vitamin D throughout the year, including people who have darker skin, spend little time outdoors or usually cover most of their skin when outside.
Tirzepatide is not known to change the amount of vitamin D you need. Vitamin D is fat soluble, so taking it with a meal that contains some fat may help your body absorb it. If your appetite is smaller while taking Mounjaro, you can take it with the meal that usually contains the most food.
More is not necessarily better. Adults should not normally take more than 100 micrograms, or 4,000 IU, of vitamin D per day unless a healthcare professional has advised a different dose. Check the strength on the label, particularly when buying high strength products online.
Calcium, Zinc and the Minerals That Need Extra Care
Calcium can contribute to constipation in some people, which may be more noticeable if you already experience constipation while taking Mounjaro.
Different calcium supplements can also be absorbed differently. Calcium carbonate is usually taken with food, while calcium citrate can be taken with or without food. If calcium causes bloating or digestive discomfort, speak to your pharmacist about whether another form may be more suitable.
Calcium and iron can affect each other's absorption when taken together. If you have been advised to take both, your pharmacist or prescriber can recommend how to space the doses.
Zinc can cause nausea, particularly when taken on an empty stomach. Taking it with food may make it easier to tolerate. Avoid taking high doses of zinc for long periods unless your doctor has recommended it, as too much zinc can cause side effects and may affect the levels of other minerals in the body.
If you take several supplements, check the labels carefully. A multivitamin may already contain calcium, zinc, vitamin D or other nutrients, so adding separate supplements can increase your total daily intake without you realising it.
Which Supplements Are Most Likely to Worsen Nausea
| Supplement | Likelihood of aggravating symptoms | What usually helps |
|---|---|---|
| Iron salts | High | Take with food, discuss alternate-day dosing or a different preparation with your prescriber |
| Zinc | High | Take with food, keep within 25mg a day |
| High-dose vitamin C | Moderate to high | Reduce the amount, use a buffered form, split across the day |
| Large multivitamin tablets | Moderate | Switch to a smaller tablet, liquid or chewable |
| Calcium carbonate | Moderate | Consider calcium citrate, split across the day |
| Fish oil | Moderate | Take with the largest meal, consider enteric-coated capsules |
| Magnesium oxide | Moderate | Switch to glycinate if stools are loose |
| Vitamin D | Low | Take with a meal containing fat |
| B vitamins | Low | Take with food if sensitive, check total B6 |
How to Time Supplements to Reduce Side Effects
Taking supplements in the right way may make them easier to tolerate while you are using Mounjaro.
- Take supplements with food where the product instructions allow it. This may help reduce nausea and stomach discomfort, particularly with supplements such as iron and zinc.
- Spread supplements across the day rather than taking several tablets at once. This may be easier on your stomach.
- If you are starting several new supplements, consider introducing them one at a time. This makes it easier to identify which product may be causing a side effect.
- Fat soluble vitamins, including vitamins A, D, E and K, are generally best taken with food. Follow the instructions on the specific product.
- If you take iron, keep it separate from calcium supplements, dairy products, tea and coffee because these can reduce iron absorption. Your pharmacist can advise you on suitable timings.
- You do not generally need to avoid supplements on the day of your Mounjaro injection. There is no established need to change your vitamin schedule around the injection. If you regularly notice a change in symptoms after your weekly dose, mention this to your prescriber.
Always follow the instructions on your supplement and ask your pharmacist or prescriber if you are unsure about timing.
Warning Signs That Are Not a Supplement Problem
Some symptoms may be blamed on vitamins or supplements when they could need medical attention. Seek same day medical advice if you experience:
- Persistent vomiting or an inability to keep fluids down.
- Severe or persistent abdominal pain, particularly if it spreads to your back.
- Confusion, unsteadiness or changes in your vision, particularly alongside very low food intake or persistent vomiting.
- Fainting, severe dizziness or a racing heartbeat.
- Possible signs of dehydration, such as very dark urine, passing urine less often than usual or ongoing light headedness.
Do not assume that changing or stopping a supplement will resolve serious symptoms. If you feel very unwell, seek medical advice promptly.
People who have had very low food intake or prolonged vomiting may be at risk of nutritional deficiencies. If you are concerned about your food intake or symptoms, speak to your prescriber, GP or pharmacist.
When to Ask for a Blood Test
Routine nutritional blood tests are not automatically required for everyone taking Mounjaro. However, testing may be worth discussing with your GP or prescriber if you have been taking treatment for several months while eating much less than usual, or if you have ongoing symptoms such as tiredness, dizziness or breathlessness.
You may also want to discuss testing if you follow a vegan or highly restricted diet, take metformin, have previously had a nutrient deficiency or have another reason to be at risk of deficiency.
Depending on your symptoms and medical history, your healthcare professional may consider tests such as vitamin B12, vitamin D, ferritin or a full blood count.
Blood tests can be more useful than taking several supplements without knowing whether you need them. If a deficiency is identified, your healthcare professional can recommend the appropriate supplement and dose.
Eligibility, Assessment and What Weight Loss Injection Treatment Costs
Mounjaro is authorised in the UK for weight management alongside a reduced calorie diet and increased physical activity. It is also authorised for the treatment of type 2 diabetes in appropriate patients.
Wegovy is also available in the UK for weight management, subject to the relevant prescribing criteria and clinical assessment. For private weight management treatment, eligibility may generally be considered from a BMI of 30 or above, or from 27 or above where a weight related health condition is present, such as high blood pressure, type 2 diabetes, abnormal cholesterol levels or obstructive sleep apnoea. Different BMI thresholds may apply to some ethnic groups.
Meeting a BMI threshold does not automatically mean that treatment is suitable. A UK registered prescriber will consider your medical history, current medicines, previous weight management treatment and other relevant factors before deciding whether a prescription is appropriate.
If you are considering prescription weight loss treatment, you will usually need to complete a medical assessment before a prescription can be issued. This may form part of an online consultation or weight management service. Make sure you tell the prescriber about every medicine, vitamin and supplement you take.
Mounjaro is supplied in a KwikPen containing four weekly doses, so one pen generally provides four weeks of treatment when used as prescribed. The dose is usually increased gradually under prescriber supervision, starting at a lower dose and moving to a higher maintenance dose if appropriate. This means the starting price may not be the same as the ongoing cost of treatment.
| Strength | Price per pen | Cost per weekly dose |
|---|---|---|
| 2.5mg | £174.99 | £43.75 |
| 5mg | £204.99 | £51.25 |
| 7.5mg | £254.99 | £63.75 |
| 10mg | £274.99 | £68.75 |
| 12.5mg | £304.99 | £76.25 |
| 15mg | £323.99 | £81.00 |
Prices shown are standard website prices and are correct at the time of writing. Prices can change, so the live pricing table at checkout should always be treated as the most up to date source. A full year of weekly treatment contains 52 doses, which would require 13 pens rather than 12. If you are planning your treatment costs, it is therefore helpful to budget based on the number of weekly doses.
Full details about storage, side effects and how to use Mounjaro are available on our page about Mounjaro treatment.
Mounjaro should be dispensed by a GPhC registered pharmacy. This provides an important check that the pharmacy is appropriately registered to supply medicines. Mounjaro requires refrigerated storage before use, with unopened pens generally kept between 2°C and 8°C and protected from freezing. Where temperature controlled delivery is used, follow the storage instructions provided with your medicine when it arrives.
Wegovy was authorised by the Medicines and Healthcare products Regulatory Agency in September 2023. Next day delivery may be available for prescription weight loss medicines, depending on the provider, stock, delivery location and the time your prescription is approved. Many providers have order cut off times, so completing your consultation and receiving clinical approval before the relevant cut off may be necessary.
Some providers may offer tracked delivery and discreet packaging. Delivery times can vary, so check the current delivery information and confirm that your prescribed strength is in stock before relying on next day delivery.
If you are still comparing your options, our overview of medically supervised weight loss explains the treatment options available in the UK and how eligibility is assessed.
Medical Disclaimer
This article is for general information only and does not constitute medical advice, diagnosis or treatment. The nutrient amounts mentioned are general UK public health reference values or safety limits and are not personalised recommendations. Your nutritional needs may be different.
Mounjaro is a Prescription Only Medicine and should only be used following an appropriate clinical assessment and under the supervision of a qualified prescriber. Whether treatment is suitable for you depends on your individual circumstances, and results can vary from person to person.
Do not start or stop a supplement, or change the dose of a prescribed medicine, based on this page alone. Speak to your GP, pharmacist or prescriber before making changes, particularly if you are pregnant, breastfeeding or planning a pregnancy, have kidney or liver disease, or take other medicines.
If you feel seriously unwell, seek urgent medical advice. NHS 111 can provide advice when you are unsure what to do. Suspected side effects from medicines can be reported through the MHRA Yellow Card scheme.
