To use GLP-1 weight loss medication safely and achieve the best results, it's important to know how to take your treatment correctly and to be aware of any potential side effects.
These treatments come in two forms: a once-weekly injection (such as Mounjaro or Wegovy) and a once-daily tablet (Wegovy oral tablets). The way you take each one is different, so with that in mind, our experts have compiled important information about how to use your treatment safely and how to manage common side effects.
Mounjaro Treatment Tutorial
Find out everything you need to know about how to safely use and store Mounjaro with this comprehensive guide to the treatment.
Wegovy Injectable Pen Treatment Tutorial
Find out everything you need to know about how to safely use and store the Wegovy injection with this comprehensive guide to your treatment.
Wegovy Oral Tablets Tutorial
Find out everything you need to know about how to take and store Wegovy oral tablets, including the important empty-stomach and timing rules, with this comprehensive guide to your treatment.
How to Take Wegovy Oral Tablets
Wegovy oral tablets are taken once a day, so the way you take them is different from a weekly injection. How and when you take the tablet matters, because taking it incorrectly can stop your body absorbing the medicine properly. Follow these steps:
- Take One Tablet on an Empty Stomach: Take it first thing in the morning, before you eat or drink anything. You should have had nothing to eat for at least 8 hours beforehand, which your overnight sleep normally covers.
- Use a Small Sip of Water: Take the tablet with no more than half a glass of water (around 120ml). Do not take it with any other drink.
- Wait at Least 30 Minutes: You must not eat, drink, or take any other oral medicines for at least 30 minutes after your tablet. After 30 minutes, you can have breakfast and take your other medicines as normal.
- Swallow the Tablet Whole: Do not split, crush, or chew it, as this affects how the medicine is absorbed.
- Take It at the Same Time Every Day: A steady routine keeps a consistent level of medicine in your body and helps you remember.
Taking the tablet with too much water, alongside food, or without the 30-minute wait can significantly reduce how much medicine your body absorbs.
If You Miss a Dose
If you forget to take a tablet, skip the missed dose and take your next tablet at the usual time the following morning. Never take two tablets on the same day to make up for a missed one.
Storing Wegovy Oral Tablets
Keep the tablets in their original blister pack until you take them, and store them out of the sight and reach of children. Unlike the injections, the tablets do not need to be kept in the fridge, but always check the storage instructions in your patient information leaflet.
Wegovy Oral Tablets Dosing Schedule
Like the injectable treatments, Wegovy oral tablets are started at a low dose and increased gradually. This step-up approach (titration) gives your body time to adjust and helps reduce side effects such as nausea.
Your prescriber will increase your dose in stages, with at least a month at each step before moving up:
- Starting Dose: 1.5mg once daily
- Second Step: 4mg once daily
- Third Step: 9mg once daily
- Maintenance Dose: 25mg once daily
You should only ever take one tablet a day. Do not take more than one tablet in a day to try to reach a higher dose. Your prescriber may keep you on a lower dose for longer if it suits you better, and 25mg once daily is the maintenance dose. Always follow the dose your prescriber has given you, and do not change it yourself.
Potential Side Effects That Are Common
As with most medications, GLP-1 weight loss treatments like Mounjaro, Wegovy injectable pens and Wegovy oral tablets may cause side effects. These side effects are often mild and tend to subside as your body adjusts to the treatment. To help, our experts have compiled this overview with practical tips on how to manage them.
Nausea/vomiting
Nausea and/or vomiting are very common side effects associated with using GLP-1 weight loss medication, affecting more than 1 in 10 individuals, particularly during dose escalation.
Tips to manage nausea and/or vomiting:
- Stay Hydrated: Drink plenty of clear fluids such as water or herbal teas.
- Eat Small, Frequent Meals: Eating your meals in smaller, more frequent portions can help reduce the side effects.
- Drink Herbal Teas: Ginger, peppermint or fennel teas can help soothe nausea.
- Avoid Strong-Smelling Foods: Strong odours can trigger or worsen nausea.
- Get Fresh Air: A short walk can help relieve symptoms and provide a distraction.
If you take the tablet: if you're being sick shortly after taking your morning tablet, do not take a replacement dose. Take your next tablet at the usual time the following day, and speak to your prescriber if vomiting continues, as it can reduce how well the tablet works.
Vomiting more than three times a day or experiencing severe symptoms like abdominal pain may indicate that the treatment is not suitable for you.
GLP-1 weight loss treatments can increase the risk of dehydration due to gastrointestinal side effects commonly associated with the treatment. It is important to be aware of dehydration symptoms like dark urine, reduced urination or lightheadedness. Make sure to drink plenty of clear fluids during the treatment and seek medical advice if these symptoms occur.
Call NHS 111 for urgent medical advice if you are unable to retain fluids or if your symptoms become worse.
Constipation
Constipation is a very common side effect associated with using GLP-1 weight loss medication that occurs in more than 1 in 10 individuals.
Tips to manage constipation:
- Stay Hydrated: Drink plenty of clear fluids such as water or herbal teas.
- Eat High-Fibre Foods: Include foods like prunes, figs, oats and whole grains in your diet.
- Take Regular Walks: Light physical activity can stimulate bowel movements.
Headaches
Headaches are a very common side effect associated with using GLP-1 weight loss medication that occurs in more than 1 in 10 individuals. However, they tend to improve after a few days or weeks of the treatment.
Tips to manage headaches:
- Rest in a Quiet, Dark Environment: Lying down in a dimly lit room can reduce sensitivity to light and noise which can help ease the symptoms.
- Use Relaxation Techniques: Meditation or scalp massage can help ease tension.
- Get Adequate Sleep: Aim for 7-9 hours of sleep every night.
Contact your GP or call NHS 111 if your headaches persist or worsen.
Diarrhoea
Diarrhoea is a very common side effect associated with using GLP-1 weight loss medication, especially at the start of the treatment. However, the symptoms tend to improve after a few doses of the treatment.
Tips to manage diarrhoea:
- Stay Hydrated: Drink plenty of clear fluids like water or herbal teas.
- Get Plenty of Rest: Allowing your body time to rest can help ease the symptoms.
Contact NHS 111 if your diarrhoea persists for more than a few days, if you are unable to tolerate or retain fluids, if you feel excessively drowsy or if you notice blood in your stools or rectal bleeding.
Heartburn
Heartburn is a common side effect associated with using GLP-1 weight loss medication and is often paired with nausea.
Tips to manage heartburn:
- Stay Hydrated: Drink plenty of clear fluids like water or herbal teas.
- Eat Small, Frequent Meals: Eating your meals in smaller, more frequent portions can help reduce pressure on the stomach.
- Avoid High-Fat or Sugary Foods: Foods that are high in fat or sugar can trigger or worsen heartburn.
Injection Site Reactions (Injectable Treatments Only)
This side effect applies to the injectable treatments only. Wegovy oral tablets are swallowed, so there is no injection site to react.
Reactions like redness, itching or swelling around the injection occur in up to 1 in 10 individuals. However, these symptoms tend to improve over the course of the treatment.
Tip to manage injection site reactions:
- Rotate Injection Sites: Switching injection sites after each dose can help avoid irritation.
Discontinue the treatment and contact your GP or NHS 111 if the rash around the injection site worsens, spreads, becomes very red or causes significant pain. Please also report any severe adverse injection site reactions to us.
Gallstones and Gallbladder Inflammation
Gallstones may occur in up to 1 in 10 individuals using Wegovy (including the tablets) or Mounjaro. Using GLP-1 weight loss treatment can also increase the risk of developing gallbladder inflammation (cholecystitis).
Seek immediate medical attention if you experience any of the following:
- Severe Abdominal Pain (especially upper right side under ribs)
- Vomiting
- High Body Temperature
- Yellowing of Your Skin or the Whites of Your Eyes (jaundice)
To reduce your risk of developing gallstones or gallbladder inflammation, maintain a steady rate of weight loss by eating small, regular meals and drinking plenty of clear fluids.
Potential Side Effects That Require Urgent Medical Attention
Although uncommon, some of the side effects associated with using GLP-1 weight loss treatment require immediate medical attention.
Pancreatitis
An uncommon but serious side effect.
Call NHS 111 or go to A&E immediately if you experience:
- Severe abdominal pain radiating to your back
- Nausea or vomiting
Anaphylaxis
A rare but life-threatening allergic reaction.
Call 999 or go to A&E immediately if you experience:
- Difficulty breathing
- Swelling of your face, tongue or throat
Sudden Vision Loss
In very rare cases, treatment with semaglutide (Wegovy) has been linked to a serious eye condition called non-arteritic anterior ischaemic optic neuropathy (NAION), which affects the optic nerve and can cause sudden loss of vision, often without any pain.
Seek urgent medical attention if you experience:
- Sudden loss of vision in one or both eyes
- Sudden partial loss or blurring of your vision
Do not wait to see if it improves. Contact your GP, call NHS 111 or attend A&E, and let your prescriber know, as your treatment may need to be reviewed or stopped.
Kidney or Bladder Stones
Kidney or bladder stones are an uncommon side effect that may affect up to 1 in 100 individuals. Signs can include pain in your back or lower abdomen, difficulty passing urine or a change in the colour of your urine.
Contact your GP or call NHS 111 if you experience these symptoms.
If you get any side effects, including any not listed here, you can report them directly through the Yellow Card scheme at yellowcard.mhra.gov.uk or via the MHRA Yellow Card app. Reporting side effects helps provide more information on the safety of these medicines.
Having Surgery, Anaesthesia or Sedation
GLP-1 weight loss treatments slow down how quickly food leaves your stomach. This means your stomach may still contain food even after a normal fasting period, which can cause problems if you have a general anaesthetic or deep sedation, for example for an operation or some dental or endoscopy procedures.
If you are due to have surgery or any procedure involving anaesthesia or sedation, you must tell the healthcare team in advance that you are taking a GLP-1 weight loss treatment. They may ask you to fast for longer or to pause your treatment beforehand. You should not stop your treatment without medical advice, but you must always mention it before any planned procedure.
GLP-1 Weight Loss Treatments and Contraception
Oral Contraception and Mounjaro
If you are using oral contraception (i.e. the combined pill or the progestogen-only pill) and taking Mounjaro (Tirzepatide), it is important to use an additional barrier method of contraception (e.g. condoms) alongside oral contraceptive pills for 4 weeks after starting the medication and for 4 weeks after any increase in the Mounjaro dose. You could also consider switching to long-acting contraceptives (e.g. IUD) while taking Mounjaro.
Please note: Diarrhoea and vomiting are common side effects of Mounjaro that can reduce the effectiveness of oral contraceptives. If vomiting occurs within three hours of taking the contraceptive pill, or if you experience severe diarrhoea for more than 24 hours, you should follow the missed pill rules as instructed in the patient information leaflet of your oral contraception. You should also consider an alternative non-oral method of contraception (e.g. IUD or condoms) if your diarrhoea or vomiting persists.
Oral Contraception and Wegovy
There is currently no evidence that Wegovy (Semaglutide), whether the injection or the oral tablets, can reduce the effectiveness of oral contraception (i.e. the combined pill or the progestogen-only pill).
Please note: Diarrhoea and vomiting are common side effects of Wegovy that can reduce the effectiveness of oral contraceptives. If vomiting occurs within three hours of taking the contraceptive pill, or if you experience severe diarrhoea for more than 24 hours, you should follow the missed pill rules as instructed in the patient information leaflet of your oral contraception. You should also consider an alternative non-oral method of contraception (e.g. IUD or condoms) if your diarrhoea or vomiting persists.
Non-Oral Contraception and Mounjaro/Wegovy
There is currently no evidence that GLP-1 weight loss treatments like Mounjaro or Wegovy (injection or tablets) can affect the effectiveness of non-oral methods of contraception (e.g. the coil, implant, injection, patch or ring). Therefore, there are no extra precautions that are needed when using these methods of contraception alongside GLP-1 weight loss treatments like Mounjaro or Wegovy.
Contraception and Switching Between Treatments
If you're switching from Wegovy (semaglutide), whether the injection or the oral tablets, to Mounjaro (tirzepatide), you'll need to take extra care with contraception. Mounjaro can temporarily reduce how well oral contraceptives (the pill) are absorbed, so while you continue your oral contraception you should also use an additional barrier method (such as condoms) for 4 weeks after starting Mounjaro and for 4 weeks after any increase in your Mounjaro dose.
Alternatively, you could switch to a contraceptive method that isn't taken by mouth, such as an IUD, implant, injection, patch or ring, as these aren't affected. This applies whichever form of Wegovy you're moving from, because the precaution relates to Mounjaro rather than to your previous treatment.
Switching between any forms of treatment, including from an injection to a tablet or from a tablet to an injection, always requires a new clinical assessment. Do not change your treatment or starting dose without guidance from your prescriber.
Oral Emergency Contraception and Mounjaro/Wegovy
It is currently unknown whether oral emergency contraception is affected by GLP-1 weight loss treatments like Mounjaro or Wegovy. The copper IUD (coil) is the most effective method of emergency contraception that is not affected by diarrhoea and vomiting, common side effects associated with taking GLP-1 weight loss treatments. If you require emergency contraception, please consult with your healthcare practitioner about all other medications you are taking, including GLP-1 weight loss treatments.
GLP-1 Weight Loss Treatments and Pregnancy or Breastfeeding
GLP-1 weight loss treatments like Mounjaro or Wegovy (injection or tablets) should not be used in pregnancy. Therefore, it is important to use effective contraception while taking GLP-1 weight loss treatment. If you become pregnant whilst taking Mounjaro or Wegovy, it is important to consult with your doctor immediately.
If you are planning to conceive, it is important to stop taking Wegovy (injection or tablets) at least two months prior and Mounjaro at least one month prior to the planned conception.
GLP-1 weight loss treatments should also not be used while breastfeeding. If you are breastfeeding or planning to, speak to your prescriber about your options before starting or continuing treatment.
GLP-1 Weight Loss Treatments and Depression/Suicidal Thoughts
There is currently no evidence of a causal association between GLP-1 weight loss treatments like Mounjaro or Wegovy (injection or tablets) and depression, suicidal ideation and suicide.