Does phentermine make you pee a lot?

Not typically. Increased urination (frequent urination) isn’t a common side effect listed for phentermine. Phentermine more often causes dry mouth, insomnia, increased heart rate or blood pressure, nervousness, dizziness, and sometimes constipation or diarrhea.

If you’re experiencing frequent urination, it could be due to other factors such as:
- Urinary tract infection or other urinary issues
- Diabetes or high blood sugar
- Caffeine or other stimulants
- High fluid intake
- Other medications or interactions
- Anxiety or stress

What you should do:
- Track your symptoms, fluids, and any other meds you’re taking.
- If you have pain with urination, blood in the urine, fever, weight changes, or if the urinary frequency is persistent or worsening, contact your clinician.
- If you’re worried about a side effect from phentermine, talk to the prescribing doctor before making changes to your regimen.

If you want, tell me any other symptoms you have or your current meds, and I can help think through possible causes.