Many people find that ear plugs hurt their ears. Some plug varieties are worse than others. Foam is probably the worst for causing ear discomfort. They lead people to look for ear plugs that don't hurt. There are several reasons for the discomfort.
1) The memory foam expands in the ear. It presses hard on the sensitive skin lining the ear canal. This causes pain. The plugs gradually push themselves out of the ears, dragging on the skin and causing abrasion. This is also uncomfortable. The skin is more likely to become infected because bugs can get in through the damaged areas.
2) Infection can lead to itching and soreness. This is another reason for ear plugs hurting.
3) Allergy. It is also possible that the plugs contain a material to which you are allergic. An additive in the plastic may cause itching and soreness.
4) Rough plugs. The rough surface on some plugs can also cause damage and so soreness in the ears. Foam can become rough after washing or after a few uses.
There are several reasons why ZenPlugs are more comfortable. Firstly, they are made from smooth thermoplastic which is not aggressive on the skin. It does not rub hard when placed into the ears. The plastic does not expand, unlike foam. This means they do not push themselves out of your ears, dragging on the skin as they go. They are also non-porous and antibacterial so are far less likely to cause infections. They are far more hygienic as they can be wiped clean as well. Because they can be remolded as often as you can perfect the fit as well as the size so that they don't protrude from your ears.
ZenPlugs are molded to your ear canals so there is no pressure effect on the delicate skin lining your ear canals. They don't expand in your ears, unlike foam ear plugs. This makes them far more comfortable.
Summary. In summary many types of earplugs can be sore with regular use. This is due to infection, irritation and pressure. ZenPlugs solve these problems by being comfortable and far more hygienic.