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What happens if you take your weight loss pill at the wrong time?
Medically reviewed by
Daniel Atkinson, GP Clinical Lead
Why does taking your weight loss pill at the right time matter?
Different types of weight loss pills work in the body differently. This means that depending on the pill you’re taking, you might need to take them at specific times of day, on an empty stomach, or after eating.
| Type of weight loss pill | Name | Timing requirements | What happens if you take it at the wrong time |
|---|---|---|---|
| Fat absorption blocker | Orlistat, Alli | Take it alongside a meal, or up to an hour after eating. | There’s no fat in your stomach to block from being absorbed, so they won’t work. |
| Oral GLP-1 | Wegovy pill | Take it first thing in the morning before eating with a drink of water. | The medicine won’t be absorbed properly by your stomach if there's food in it, and treatment may be ineffective. |
| Small-molecule non-peptide oral GLP-1 | Foundayo | Foundayo doesn’t have any specific timing requirements, and you can take it at any time. | Because Foundayo is a small-molecule chemical compound, it isn’t broken down by stomach acid or digestive enzymes, so you can take it any time of day, with or without food. |
| Appetite controllers | Mysimba | Take it when you eat a meal. | Taking Mysimba on an empty stomach can increase the risk of side effects like stomach irritation, nausea, and constipation. |
What should you do if you miss taking your weight loss pill?
It depends on the tablet you’re taking and how long it’s been since you missed your dose.
- If you’ve forgotten to take a fat absorption blocker like Orlistat, if it’s been less than an hour since you last ate, you can take it as soon as you remember. If it’s been more than an hour since you ate, the food and fat have already been digested and absorbed, so skip the missed tablet and carry on as normal from your next meal.
- If you’ve missed your Wegovy pill, skip the pill you missed and then carry on as normal from your next upcoming dose. Don’t take a double dose to make up for the missed one. If you’ve missed more than a few days of your Wegovy pill in a row, speak with your clinician before restarting treatment.
- If you’ve missed your dose of Mysimba, skip the missed dose and carry on as normal from your next scheduled pill. Don’t take a double dose because it won’t have any benefit, and could increase your risk of side effects.
What are the risks of taking weight loss pills at the wrong time?
Taking your pill at the wrong time could increase the risk of experiencing side effects, or impact the effectiveness of your treatment, which could cause food cravings to come back.
Efficacy is reduced
Fat absorption blockers (Orlistat, Alli) work by reducing the amount of fat your digestive system absorbs from meals by about 30%. But it only works if you take it with food, or within an hour of eating, otherwise there isn’t any food (and fat) in your stomach to prevent from being absorbed. So if you take it on an empty stomach, it won’t have any benefit, but you may still experience side effects.
Oral GLP-1s (Wegovy pill) need to be taken on an empty stomach because of the way the medicine is absorbed. Wegovy pills contain something called SNAC technology, short for sodium N-(2-hydroxybenzoyl) amino caprylate. It protects the pill from stomach acid and digestive enzymes, while temporarily increasing the local absorption through the stomach lining, which helps Wegovy last long enough in your stomach to be absorbed into your bloodstream.
Eating or drinking before you take your tablet can lower the concentration of SNAC and trigger stomach acid and digestive enzymes, which can cause Wegovy to break down in your stomach before it’s absorbed, reducing its effectiveness.
Appetite controllers (Mysimba) should be taken with food because this can reduce side effects (like stomach irritation and nausea), but it can also improve how well your body absorbs the medication. This can help to maintain a more stable absorption rate, meaning the levels of medicine in your body are more steady over time.
Unpleasant side effects
Taking Mysimba on an empty stomach can increase your risk of experiencing side effects. The most common Mysimba side effects are nausea, vomiting, constipation and headache. It’s because Mysimba works by targeting parts of your brain and gastrointestinal system, which can affect how food moves through your gastrointestinal tract and bowel movements.
Taking Mysimba with food slows down how quickly the medicine is absorbed, so its levels don’t suddenly spike in your body. Bupropion, one of Mysimba’s active ingredients, is thought to work by increasing chemicals in your brain that reduce appetite and cravings, but this can also affect the “sickness centre” of your brain. Eating food with your treatment can lessen this impact, and can help with feelings of nausea.
Making sure you take your Wegovy pill at the same time every day may also help to alleviate common side effects like nausea, abdominal discomfort, and headaches. Maintaining a regular schedule keeps the levels of Wegovy in your body steady, which gives your body a chance to get used to the medicine without any sudden increases or decreases. And as your body adapts to the treatment, these side effects should fade.
Return of cravings
And if you miss your Mysimba or Wegovy pills, or take them at the wrong time, the levels of the medicine in your body can fluctuate. This can lead to sudden spikes in hunger, cravings, and “food noise” (which is intrusive thoughts about food) before your next scheduled dose. Sudden, unexpected cravings can lead to binge eating, going off your diet plan, and slow down your progress.
Tips to take your pill at the right time
When to seek medical help
If you accidentally take too much of your medicine, seek medical advice immediately. If your side effects become unmanageable (like persistent headaches, nausea and vomiting, stomach pain, or constipation) call 111, or speak to your clinician. Depending on the treatment you’re using, they may be able to reduce your dose or suggest an alternative medicine to see how you respond.
Reference Popover #ref1
Treated trusted source
Bansal, A.B. Patel, P. Khalili, Y.A. (2024).
Orlistat. StatPearls. Treasure Island (FL): StatPearls Publishing.
Reference Popover #ref2
Treated trusted source
Novo Nordisk. (n.d.)
YOUR COMPLETE GUIDE TO WEGOVY® PILL. Wegovy.com.
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