What happens to your blood pressure on Foundayo
In clinical trials, Foundayo led to consistent reductions in blood pressure until around week 24, with most of the reduction occurring in the first 3 months.
After week 24, average readings rose slightly while participants continued taking Foundayo.2
A blood pressure reading has two numbers, measured in mmHg (millimetres of mercury).
The top number (systolic) is the highest pressure when our heart pumps, and the bottom number (diastolic) is the lowest pressure when it relaxes between beats.
High blood pressure is generally considered 140/90 or higher at a GP surgery, or 135/85 or higher at home.
The table below shows the average change in systolic blood pressure in two large Foundayo trials.
ATTAIN-1 included people without type 2 diabetes, and 39.5% of them had high blood pressure.
ATTAIN-2 included people living with type 2 diabetes, and 74.5% of them had high blood pressure.2
| Week |
Foundayo (mmHg) |
Placebo (mmHg) |
| 4 |
-2.8 |
-0.6 |
| 12 |
-5.8 |
-1.3 |
| 24 |
-7.3 |
-2.2 |
| 48 |
-6.9 |
-1.1 |
| 72 |
-5.8 |
-1.5 |
Source: FDA review, Figure 23. The figures combine all doses from ATTAIN-1 and ATTAIN-2, and show the average for people measured at each visit.
Diastolic blood pressure reduced by less, with the largest average reduction of 2.3 to 2.7 mmHg in the weight management trials.1
By week 12, systolic blood pressure had already fallen by an average of 5.8 mmHg, yet people taking the highest dose in ATTAIN-1 had lost about 5% of their body weight, and by week 48 they’d lost about 12.7%.2
So, blood pressure seemed to drop well before most of the weight loss was achieved. This is likely explained by reductions in insulin and liver fat levels, both of which contribute to blood pressure.
Weight loss is often credited with reductions in blood pressure. However, it may not be total weight loss per se, but site-specific weight loss (like liver fat reduction), along with other physical improvements that occur when we lose excess body fat, such as improved blood sugar and lower insulin levels.
Participants in the lowest-dose group took the same Foundayo dose from week 8 onwards, but their average systolic blood pressure continued to fall.
At week 8, their average systolic blood pressure was 4.6 mmHg lower than before treatment. By week 24, it was 6.7 mmHg lower.2
Average readings before treatment were about 126/81 in ATTAIN-1 and about 131/82 in ATTAIN-2.2 Both are below 140/90, so we can’t use the average reductions in these trials to predict how much Foundayo will lower your blood pressure if it’s still high.
Can Foundayo cause low blood pressure if I take blood pressure medication?
Low blood pressure was reported more often in people taking Foundayo with blood pressure tablets.
The Foundayo prescribing information says your doctor may need to change the dose of your blood pressure tablets, and the UK prescribing information warns that Foundayo can cause low blood pressure.1
You can still take Foundayo with blood pressure tablets, but your GP should review the dose of your blood pressure tablets.
Low blood pressure is when you record a reading under 90/60. It can make you feel dizzy, sick, weak, or confused, and it can blur your vision or make you faint.
In ATTAIN-1 and ATTAIN-2, 2.3% of people taking Foundayo reported low blood pressure, compared with 0.4% on placebo.2
About half of the people taking Foundayo in the trials were also on blood pressure tablets.
About 3.5% of people taking Foundayo with blood pressure tablets reported low blood pressure, compared with 1.1% of people taking Foundayo without blood pressure tablets.2
On placebo, fewer than 1 in 200 people reported low blood pressure, whether they took blood pressure tablets or not.2
Taking blood pressure medication alone doesn’t fully explain why low blood pressure was more common in people also taking Foundayo.
Foundayo may lower blood pressure further through its effects on weight and insulin levels, so some people may need a lower medication dose.
Of the 72 people who reported low blood pressure in ATTAIN-1 and ATTAIN-2, 55 had mild cases, 15 moderate, and 2 severe.
Both severe cases had another possible cause. One person had an irregular heartbeat called atrial fibrillation, and the other may have taken an extra dose of a blood pressure tablet by mistake.2
The UK prescribing information for Mounjaro and Wegovy doesn’t warn that low blood pressure is more common in people taking blood pressure tablets. Their leaflets don’t advise changing blood pressure tablet doses.
Low blood pressure is listed as a common side effect of Foundayo and Mounjaro (up to 1 in 10 people) and an uncommon side effect of Wegovy (up to 1 in 100).1
However, we can’t tell whether Foundayo causes low blood pressure more often than Mounjaro or Wegovy, because no study has directly compared the three medicines.
The U.S. prescribing information for Foundayo includes the ATTAIN-1 and ATTAIN-2 results, but it doesn’t include a separate warning about low blood pressure in people taking blood pressure tablets.4
Follow the UK advice to have your blood pressure tablet doses reviewed, even if U.S. advice doesn’t mention a dose review.
Our guides to Mounjaro with high blood pressure and Wegovy with high blood pressure explain how the injections affect blood pressure.
When to have your blood pressure medications reviewed
We recommend asking your GP to review your blood pressure medications once before your first Foundayo tablet, then checking your blood pressure at home for 6 months, as most of the reduction happens in the first 3 months.
At that review, ask whether any of your tablets should change before you start, and what blood pressure reading you’re aiming for.
The checks below, including contacting your prescriber if your top number is 20 mmHg or more below your usual reading, are our suggestion based on the blood pressure results, as no prescribing information or NICE guidance sets a schedule.
Blood pressure tablets are usually prescribed by your GP, while Foundayo is prescribed privately, so you may have two prescribers. Tell both which medicines you take before you start, and agree which one you’ll contact if your readings change.
NICE advises using a validated monitor, and the British and Irish Hypertension Society keeps a list of them.
To measure your blood pressure, sit quietly with your arm outstretched and supported, and use a cuff that fits your arm.
If you don’t have a monitor, we’d recommend speaking with your local pharmacist. Most pharmacies can check your blood pressure, but some may charge you for it.
- Before your first Foundayo tablet, take two readings a minute apart, morning and evening, for a week. Write them down, leave out the first day, and work out the average. This is your usual reading.
- For the first 6 months, repeat this routine for at least 4 days each month, even if your Foundayo dose stays the same, and after each dose increase.
- After 6 months, keep checking while you’re losing weight, and check again if you feel dizzy. The four cases of low blood pressure the FDA described in detail happened about 7 to 17 months after people started treatment.2
- Contact the prescriber you agreed on if a repeat reading is under 90/60, the top number is 20 mmHg or more below your usual reading, or you feel dizzy, as your tablets may need to be reduced.
NICE‘s target for home readings is an average below 135/85, or below 145/85 if you’re 80 or over. If your average stays above that, your tablets may need to stay the same or go up, so share your readings with your GP.
If you feel dizzy when you stand up, ask your GP to compare your blood pressure sitting or lying down with a reading after at least 1 minute of standing.
If the top number falls by 20 mmHg or more, or the bottom number by 10 mmHg or more, after standing, NICE advises looking for the cause, including your medicines.
A lower blood pressure reading is usually good news because it puts less stress on your arteries, but your medications still need to be the right dose for your ongoing treatment.
How your blood pressure tablet doses might change
We don’t yet know how often people on Foundayo reduce their blood pressure tablets, or by how much. ATTAIN-1 recorded these changes, but we couldn’t find any published results.5
If your readings stay low or you feel dizzy, your GP may lower the dose or change the drug.
Your GP will also look at why you take it, as some of these tablets are also used for heart failure or after a heart attack.
Evidence on reducing blood pressure medication during weight-loss treatment comes from three trials of Wegovy (semaglutide) 2.4 mg involving 3,136 people.
Among people with a reading above 130/80, a diagnosis of high blood pressure, or blood pressure tablets, 10.9% reduced or stopped their tablets, compared with 5.2% on placebo.3
Only about two-thirds of this group were taking blood pressure tablets, so among those who were, the share who reduced or stopped their medication is probably higher than 10.9%.
These results are only a rough guide to what may happen on Foundayo, as the trials tested a different medicine in people without diabetes.
Taking Foundayo with different blood pressure medicines
Foundayo can lower blood pressure enough that your usual dose of blood pressure medication becomes too high. Your GP may need to reduce the dose if your readings stay low or you feel dizzy.
ACE inhibitors, angiotensin receptor blockers (ARBs), and water tablets also increase the risk of kidney problems if vomiting or diarrhoea causes dehydration. The list below explains the risks for each medicine type and when to contact your GP.
- ACE inhibitors (such as ramipril and lisinopril) and ARBs (such as losartan and candesartan) can make it harder for our kidneys to filter blood if we become dehydrated. If you develop vomiting or diarrhoea, contact your GP the same day, or NHS 111 if the surgery is closed.
- Water tablets, or diuretics (such as indapamide and bendroflumethiazide), increase the amount of water we pass in urine. Vomiting or diarrhoea can cause further fluid loss and dehydration. Contact your GP the same day if you develop either symptom, or NHS 111 if the surgery is closed.
- Calcium channel blockers (such as amlodipine) and alpha blockers (such as doxazosin) widen our blood vessels. Foundayo may lower blood pressure further. Check for readings below 90/60, a systolic reading (the top number) at least 20 mmHg below your usual reading, or dizziness when you stand up. If your readings stay low or you feel dizzy, ask your GP to review your dose.
- Beta blockers (such as bisoprolol) slow your heart rate. Your pulse can be normal even when your blood pressure is low, so check your blood pressure if you feel dizzy. Ask your GP to review your medication if your readings stay low or the dizziness continues.
Don’t stop these medicines yourself unless your GP has told you to. A written sick day plan can set out which medicines to pause, if any, and when to restart them.
No study has reported results for individual blood pressure medicines taken with Foundayo, and the UK prescribing information doesn’t advise on specific medicines. The explanations above are based on how each type of medicine works.1
When to take Foundayo and blood pressure medication
You can take Foundayo at any time of day. The UK prescribing information doesn’t specify a time gap between Foundayo and blood pressure medication.1
Foundayo slows stomach emptying, which can delay the absorption of other medicines into the bloodstream. The delay in stomach emptying is greatest after the first dose and becomes smaller with continued treatment.1
Computer modelling described in the UK prescribing information predicted that slower stomach emptying wouldn’t change the absorption of commonly used medicines enough to affect treatment.
However, no study has measured how Foundayo affects the absorption of blood pressure medication.1,2
If you also have heart failure
Foundayo isn’t recommended for people with the most severe heart failure (NYHA class IV), because there are no clinical data on its use in this group.1
Some blood pressure medicines are also prescribed for heart failure. Tell your Foundayo prescriber if you take your medication for heart failure as well as high blood pressure.
Foundayo with diltiazem or verapamil
Foundayo’s UK prescribing information doesn’t name diltiazem or verapamil, and it sets no Foundayo dose limit for people taking them.1
We still recommend telling your prescriber before your first Foundayo tablet, as either medicine may raise Foundayo levels in your blood.
Diltiazem and verapamil are used for high blood pressure and angina (chest pain), and verapamil also treats irregular heart rhythms.
Our body mainly clears Foundayo using a liver enzyme called CYP3A4. The UK prescribing information limits Foundayo to 9 mg with certain medicines that strongly slow this enzyme, including the antibiotic clarithromycin.1
Verapamil and diltiazem are calcium channel blockers that moderately slow CYP3A4, according to the U.S. prescribing information for Foundayo4 and the UK prescribing information for diltiazem.
The only estimate of how much these medicines raise Foundayo levels comes from a computer simulation in the U.S. prescribing information.4 It predicted that verapamil 80 mg three times a day would double Foundayo levels, but didn’t include higher doses or diltiazem.2
That prediction hasn’t been checked in people, and the FDA concluded that no dose change was needed.2
If Foundayo levels rise, side effects such as nausea are likely to be worse, so tell your prescriber if your side effects get worse after a dose increase.
Doctors running ATTAIN-1 were told to consider other medicines instead of diltiazem or verapamil where possible.5 We couldn’t find how many people in the trials took either medicine, so we have little information on how safe it is to take them with Foundayo.
Diltiazem and verapamil also lower blood pressure, so the UK warning about low blood pressure applies to both.1
If you’re sick while taking ramipril or a water tablet
If you’re being sick or have diarrhoea while taking ramipril, losartan, or a water tablet, we recommend contacting your GP the same day, or NHS 111 if the surgery is closed.
Take small, frequent sips of fluid. Don’t stop any tablets yourself unless your sick day plan says to. This is written advice from your GP on whether to pause any tablets when you’re ill.
Nausea, vomiting, and diarrhoea are the most common side effects of Foundayo. In the weight management trials, 60.1% to 68.7% of people taking Foundayo reported them, compared with 36.3% on placebo.
These side effects are more common as the dose is increased. Most were mild or moderate, and 3.9% were severe.1
Tell your Foundayo prescriber too, as the UK prescribing information says to consider changing the dose or stopping Foundayo if these symptoms are severe. They can cause dehydration, which can lead to acute kidney injury, a sudden fall in how well our kidneys work.1
ACE inhibitors and ARBs reduce the pressure our kidneys use to filter blood, and water tablets remove fluid, so losing fluid through vomiting or diarrhoea can make it harder for our kidneys to filter blood.
The NHS advises telling your doctor if vomiting or diarrhoea is due to a stomach bug or illness, as you may need to stop ramipril for a while.
Before you start Foundayo, we recommend asking your GP for a sick day plan. It should say which tablets to pause, if any, and when to restart them, including any diabetes medicines you take.
NICE advises doctors to consider temporarily stopping ACE inhibitors and ARBs in people with vomiting or diarrhoea until they’ve improved.
The UK Kidney Association calls this controversial, as the evidence is weak and stopping these tablets can worsen the condition they treat, so your GP will decide based on your own risk.
In 2023, a panel of 26 clinicians agreed that ACE inhibitors, ARBs, and water tablets should be stopped temporarily during this kind of illness, then restarted within 24 to 48 hours after symptoms clear and normal eating and drinking return.6
That was expert agreement written to guide future studies, so follow your GP’s plan.
Contact NHS 111 or ask for an urgent GP appointment if you’re peeing less than normal, your pee is dark yellow, you feel unusually tired, you’re breathing quickly or have a fast heart rate, or you feel dizzy when you stand, and it doesn’t go away.
Call 999 or go to A&E if you have signs of dehydration and you’re confused, very sleepy, or struggling to breathe, or your skin feels cold or looks blue, grey, pale, or blotchy.
Dizziness, fainting, and heart rate
In ATTAIN-1 and ATTAIN-2, 4.3% of people taking Foundayo reported dizziness, compared with 2.7% on placebo.2 It can come from low blood pressure or dehydration. If you take insulin or a sulfonylurea (a type of diabetes tablet), it can also be a sign of low blood sugar.
If you feel dizzy, lie down, then sit until you feel better, and don’t drive or use machinery until the dizziness passes. Check your blood pressure afterwards, and contact your GP or prescriber. To help prevent dizziness, stand up slowly and avoid changing position suddenly.
Foundayo also increase our heart rate. Measured sitting down in the trials, the average increase was greatest during dose increases, at 6.7 to 8.6 beats a minute, and had fallen to 3.9 to 5.2 beats a minute above the starting rate by week 72.1,2
Heart rate rose above 100 beats a minute at two or more visits in a row in 2.68% of people on Foundayo, compared with 1.23% on placebo.1
Palpitations are a pounding, fluttering, or irregular heartbeat. See your GP if you keep experiencing them. Call 999 or go to A&E if they don’t go away, or if they come with chest pain, shortness of breath, or feeling faint.
Call 999 if someone faints and can’t be woken within 1 minute, hasn’t fully recovered, has difficulty speaking or moving, or isn’t breathing.
Also call if they have chest pain or a pounding, fluttering, or irregular heartbeat, are seriously hurt, have a seizure, or have fainted while exercising or lying down.
If you’ve fainted and none of these applies, see your GP.
If worrying about your blood pressure readings keeps you awake or makes you check repeatedly, tell your GP.
Our guides on Foundayo side effects, tiredness, and heart rhythm medications cover these topics in more detail.
Food, fluids, and exercise with high blood pressure
Base meals on whole foods and season to taste
We recommend eating a diet based mainly on whole foods and seasoning your food to taste. If it tastes too salty, add less next time.
In the UK, most of the salt in our diets comes from ultra-processed foods, such as ready meals, processed meats, and savoury snacks.10
Cooking with whole foods means you have control over how much salt goes into your meal. You can also use herbs, spices, garlic, or lemon for flavour.
Check before using potassium-based salt substitutes
We recommend avoiding salt substitutes containing potassium chloride, such as LoSalt, if you take an ACE inhibitor or ARB, or if you’re older, living with diabetes, or living with kidney disease.
These products can make blood potassium levels too high, particularly with medicines such as ramipril. Use herbs, spices, or lemon to add flavour instead.
Stay hydrated while taking blood pressure medication
If you’ve been given a daily fluid limit, follow it. Otherwise, we recommend drinking regularly throughout the day, particularly while your Foundayo dose is increasing.
Vomiting and diarrhoea are more common during dose increases and can cause dehydration. If you take blood pressure medication, dehydration can lower your readings further.1
If you’re vomiting or have diarrhoea, take small, frequent sips of fluid. Contact your GP the same day if you take an ACE inhibitor, ARB, or water tablet, or NHS 111 if the surgery is closed.
Use regular activity to help lower blood pressure
We recommend regular walking, cycling, swimming, or strength exercise to help lower blood pressure alongside any medication you’re prescribed.7
If you’re not currently active, a 10-minute walk after dinner is a practical starting point. Gradually extend the walk or add another short walk as it feels manageable.
For strength exercise, try standing up from a chair repeatedly or lifting light weights. Breathe throughout each movement, as holding your breath while lifting can sharply raise blood pressure.11
If you feel dizzy during activity, stop and sit down. Ask your GP to review your medication if the dizziness continues or your blood pressure readings stay low.
Take home message
In clinical trials, Foundayo lowered blood pressure, with most of the reduction occurring in the first 3 months.2
We recommend asking your GP to review your blood pressure medication before starting Foundayo, as you may need a lower dose during treatment. Check your readings at home for the first 6 months and continue while you’re losing weight.
Tell your GP and Foundayo prescriber which medicines you take and at what doses. Agree who will review your readings and arrange any changes to your blood pressure medication.
Contact your GP or prescriber if your readings stay low, you feel dizzy, or you become dehydrated. Don’t change or stop your blood pressure medication without medical advice.
At Second Nature, we see blood pressure improvements as a benefit of treatment alongside weight loss. The aim is to reach the blood pressure target agreed with your GP.
Second Nature’s programme combines GLP-1 medication with support from registered dietitians and nutritionists, who help members eat enough protein when their appetite is low and build meals around our balanced plate.
A peer-reviewed study published in JMIR Formative Research found an average weight loss of 19.1% at 12 months among active subscribers on our semaglutide-supported programme.9
Among members with recorded 12-month weights, 77.7% lost at least 10% of their starting weight.
Second Nature's Mounjaro and Wegovy programmes
Second Nature provides Mounjaro or Wegovy as part of our Mounjaro and Wegovy weight-loss programmes.
Why choose Second Nature over other medication providers, assuming you're eligible?
Because peace of mind matters.
We've had the privilege of working with the NHS for over eight years, helping people across the UK take meaningful steps toward a healthier, happier life.
Our programmes are designed to meet people where they are, whether that means support with weight loss through compassionate one-to-one health coaching, or access to the latest weight-loss medications (like Mounjaro and Wegovy) delivered alongside expert care from a multidisciplinary team of doctors, psychologists, dietitians, and personal trainers.
At the heart of everything we do is a simple belief: real, lasting change comes from building better habits, not relying on quick fixes. We're here to support that change every step of the way.
With over a decade of experience, thousands of lives changed, and a long-standing record of delivering programmes used by the NHS, we believe we're the UK's most trusted weight-loss programme.
We hope to offer you something invaluable: peace of mind, and the support you need to take that first step.
