Demand for salt is price inelastic because there are very few substitutes for salts. Likewise, surgery has no good substitutes. When the fraction of income spent on a good is small, people don't pay much attention to the price change. Hence, demand is price inelastic.

Is salt a perfectly inelastic demand?

The demand for salt is inelastic because the demand for salt remains constant regardless of price changes. Inelastic demand is most commonly found for essential products such as salt, sugar, and milk.

What products have inelastic demand?

The most common goods with inelastic demand are utilities, prescription drugs, and tobacco products. In general, necessities and medical treatments tend to be inelastic, while luxury goods tend to be the most elastic. Another typical example is salt.