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Why do weight loss injections make you thirsty?
Medically reviewed by
Alexandra Cristina Cowell, Writer & Clinical Content Reviewer
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Medically reviewed by
Dr Alexandra Cristina Cowell
Writer & Clinical Content Reviewer
on Jun 02, 2025.
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Last updated on Dec 05, 2025.
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1. Consuming less water in foods
Weight loss injections (WLIs) can reduce your appetite, making you less likely to overeat. This may increase your thirst since you’re getting less hydration from food.
A US study found that around 19% of water intake comes from food. So eating less might result in lower water consumption overall.
Solution: Eat more ‘watery’ foods like cucumbers and watermelon. These foods have less fiber, so they’ll be easier to digest, while keeping you hydrated.
2. Overall lifestyle changes
If you’re exercising while on WLIs, you might notice you’re feeling thirstier. Exercising can produce heat, which is lost through sweat. As you sweat, you lose water, which can lead to dehydration.
Additionally, if you’re exercising strenuously, you might be breathing harder, causing further water loss through water vapor.
All of these factors can dehydrate you and trigger your thirst mechanism.
Solution: Drink water regularly when working out.
3. Gastrointestinal side effects of weight loss injections
Nausea, vomiting and diarrhea are all common side effects of WLIs. You’ll often get them during the first few weeks, and they should settle as your body adjusts to the medication.
These side effects can lead to fluid loss, making you thirsty. It’s important to drink water after vomiting or diarrhea to prevent dehydration.
Solution: Electrolytes can help hydrate your body quickly and effectively after vomiting or diarrhea.
4. Low blood pressure
WLIs may lower your blood pressure, whether that’s by losing weight or regulating your blood sugar.
To raise your blood pressure, your body might trigger thirst signals, prompting you to drink more water. This helps increase your blood volume, which elevates blood pressure levels.
Maintaining healthy blood pressure is essential, as low levels can make it more difficult for your heart to pump blood and essential nutrients throughout your body.
Solution: Drink water regularly throughout the day. If you have a blood pressure cuff at home, use it often and let your doctor know if your levels are low so they can treat it promptly.
5. Increased metabolism
While limited evidence suggests WLIs can increase metabolism, a faster metabolism can indirectly lead to thirst.
You’re more likely to generate heat, which is lost as sweat, have faster kidney function, or burn more fat, all of which might cause thirst.
Solution: Drink plenty of water and limit alcohol and sugary drinks, as these can cause dehydration.
6. Dry mouth can trigger thirst
Some weight loss injections can cause dry mouth. This can activate thirst signals in your brain, even if you’re not actually dehydrated.
Solution: Take regular sips of water. Suck on hard candies or ice cubes to stimulate saliva production.
Reference Popover #ref1
Treated trusted source
McKiernan, F., Houchins, J. A., & Mattes, R. D. (2008).
Relationships between human thirst, hunger, drinking, and feeding. Physiology & Behavior, 94(5), 700.
Reference Popover #ref2
Treated trusted source
Leib, D. E., Zimmerman, C. A., & Knight, Z. A. (2016).
Thirst. Current Biology : CB, 26(24), R1260.
Reference Popover #ref3
Treated trusted source
Ryan, O., et al. (2024).
GLP-1 therapy increases visceral adipose tissue metabolic activity: Lessons from a randomized controlled trial in obstructive sleep apnea. Obesity, 32(11), 2077-2081.
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