When you eat rotten food in Kingdom Come Deliverance you will get food poisoning (indicated by the red color on the freshness counter). Food with less than 50% freshness will poison you. Once poisoned, you will see a "skull-icon" above your health bar. This will make your health decrease over time. Very severe food poisoning will make your health drop for a longer period of time.

How to Cure Food Poisoning

Simply sleep in a bed! Yes it's that easy. Sleeping negates the food poisoning and even gives you +10 health per hour slept.

Alternatively, you can also consume an Antidote Potion. Those can be bought from apothecary shops (for example in Rattay). Good for when you're on the go.

Unlock the perk "Human Dustbin" from the Vitality skill tree (requires Vitality stat at level 6). It negates all food poisoning, even for the most rotten of foods. You'll never suffer from food poisoning again with this perk.

The further the freshness level drops towards 0 the more poisoning the food becomes.

As a general rule of thumb, avoid eating foods with less than 50 freshness (red value), unless you are standing next to a bed. Rotten food can still be resold so it's not completely useless. Food in the range of 30-50 freshness will give you minor poisoning if you consume it in small quantities and you don't have to worry too much about that when health is full.