🔬 Mechanism #1: PG & VG Are Hygroscopic

The two main ingredients in e-liquid — propylene glycol (PG) and vegetable glycerin (VG) — are both hygroscopic. That means they naturally attract and absorb water molecules from their surroundings.

When you inhale vape vapor, tiny droplets of PG and VG come into direct contact with the moist lining of your mouth, throat, nasal passages, and lungs. These compounds pull water out of your tissues and into the vapor, which you then exhale.

The result? Your mouth and throat feel dry. For most people, this is a mild, temporary effect. But if you vape a lot throughout the day and don't drink enough water, it can add up.

🧪 Mechanism #2: Nicotine Is a Diuretic

Nicotine is a mild diuretic — a substance that increases urine production. It does this by inhibiting the release of antidiuretic hormone (ADH, also called vasopressin), which normally tells your kidneys to reabsorb water instead of flushing it out.

This means that when you vape nicotine, you lose more water through urination than you normally would. The effect is similar to drinking coffee or alcohol, though nicotine's diuretic effect is milder than either.

For people who vape heavily — especially high-nicotine products like pod systems and disposables — the diuretic effect can contribute to overall dehydration throughout the day.

For more on how nicotine affects your body, see our guide to vaping and sleep, which covers the full range of nicotine's effects.