Viscosity Ranking: Water, Blood, Paracetamol Suspension, Honey

Viscosity (resistance to flow) at 20–25°C, from lowest to highest:

1. Water: ~1.0 mPa·s. Small molecules, minimal intermolecular friction.
2. Blood: ~3–4 mPa·s (hematocrit 40–45%). Non-Newtonian: shear-thinning (viscosity ↓ as shear rate ↑). Cells (RBCs, WBCs, platelets) in plasma increase viscosity 3–4x water.
3. Paracetamol suspension: ~10–100 mPa·s (varies by formulation). Solid drug particles (1–50 µm) in viscous carrier (syrup, cellulose gums). Higher solid loading = higher viscosity.
4. Honey: ~2,000–10,000 mPa·s. Supersaturated sugar solution (fructose/glucose ~80%) + hydrogen bonding + colloidal particles. Strongly shear-thinning.

Why This Order?

• Molecular size & interactions: Water < dissolved proteins/cells < suspended particles < concentrated sugar matrix.
• Non-Newtonian behavior: Blood and honey thin under stress (shear-thinning)—important in capillaries and swallowing.
• Temperature dependence: All decrease with warming; honey dramatically so.

Clinical Relevance

• IV fluid choice: crystalloids (water-like) vs. colloids (higher viscosity).
• Drug delivery: suspension viscosity affects dosing accuracy, syringeability, gastric emptying.
• Swallowing disorders: honey-thick liquids (IDDSI level 3) for dysphagia.
• Microcirculation: blood viscosity impacts perfusion, especially in polycythemia, hyperproteinemia.