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Managing side effects when using GLP-1 medications for obesity treatment

28 May 2026 • 5 minute read • medications • Lynette Amirault

Managing side effects when using GLP-1 medications for obesity treatment

Medications to treat obesity, like all medications, can have side effects. Some people experience very little side effects, and rarely some people have more side effects. The majority of people using GLP-1 medications experience SOME side effects, usually at the beginning of treatment, or when the dosage is increased.

Most often, the side effects are mild-to-moderate and get better with time.

The most common side effects are GI-related, which can be attributed to how the medications slow down gastric emptying. The same mechanism that helps a person feel fuller sooner, and stay fuller longer, can cause a number of GI discomforts, including:

  • Nausea (and if it gets bad enough vomiting)
  • Feeling overly full after a meal
  • Heartburn (especially if you have a history of heartburn)
  • Changes to bowel patterns like diarrhea or constipation

Additionally, some people will report other side effects like headache or fatigue.

General recommendations to decrease the risk or severity of side effects include:

  • Eating smaller meals more often
  • Eating slowly and stopping eating the moment you feel full
  • Do not skip meals or go too long without eating
  • Drinking lots of water
  • Avoiding high fat foods
  • Including fibre in your diet

Side effect specific recommendations:

Nausea / vomiting – this is the most commonly reported side effect, which typically occurs more in the beginning, when the dose is increased, or the first few days after the injection. Eating small amounts of bland foods every 3-4 hours can be very helpful, as nausea can happen both when the stomach is full, or when it is empty. Another significant cause of feeling nauseated or vomiting is when larger portions of high fat foods are consumed. It also naturally slow gastric emptying, so when that natural effect is combined with a GLP-1 medication it can lead to significant discomfort. Limiting high fat foods to small portions is important if you are experiencing nausea after meals.

Diet gingerale, ginger tea or ginger candies can be helpful to manage generalized nausea, as well as over-the-counter ginger tablets, or other medications like Gravol. If these tips don’t help, speak to your provider for a prescription-strength nausea medication or consider stepping down to the previously tolerated dose, and increasing more slowly.

Feeling too full – this is also very frequently reported, especially in the beginning stages of treatment when people continue to eat the same serving sizes out of habit and then become uncomfortably full afterwards. The solution to this is twofold: start choosing smaller servings, and eat more slowly with less distractions, paying close attention to how you feel during the meal. If at any point you pause to take a deep breath and sigh while eating, that is your body’s very subtle clue that your stomach is full. Once this occurs, enjoy another bite or two then put the rest away for later. Another significant cause of feeling too full is when large portions of high fat foods are consumed, because they also naturally slow gastric emptying, so when that natural effect is combined with a GLP-1 medication it can lead to a feeling of a brick sitting in the stomach.

Heartburn – or acid reflux is often made worse for people who already suffer with this condition. If you have been prescribed a medication for your acid reflux, be sure to take it regularly and speak to your prescriber if it is not managing the symptoms. Unlockfood.ca has an excellent resource on Diet Tips for Managing Your Heartburn or Acid Reflux - Unlock Food

Diarrhea – eating small meals at regular times, avoiding high fat foods, drinking lots of fluid, and including soluble fibre can help prevent and manage diarrhea. Find more information on soluble fibre here: Facts on Soluble Fibre - Unlock Food

Constipation – this side effect commonly occurs due to the slowing down of the GI system combined with a subconscious decrease in the amount of fluid being consumed. This is why drinking lots of water, eating regular meals, and ensuring regular fibre intake is important. For more information see: Managing and Preventing Constipation in Adults - Unlock Food

Headache or fatigue – some people will report these side effects that are not GI related, so it’s important to eliminate nutrition-related causes. Again, eating regular meals to ensure you are nourishing your body, and drinking lots of water can help reduce the risk of dehydration-induced or low energy availability headache or fatigue.

Final thoughts

Side effects can feel discouraging at first, but they are often temporary and manageable with the right strategies. Making small adjustments to how and what you eat, staying hydrated, and increasing doses gradually can make a significant difference. If side effects persist or interfere with daily life, your healthcare team can help tailor your treatment so you can continue safely and comfortably.