You might want to avoid garlic before bed if you�re sleeping with a partner, but it�s best avoided for reasons besides bad breath. Garlic is known as a �hot herb,� and, along with spicy food, it tends to have some properties in it that can cause heartburn. It�s known to sometimes have the side effect of upsetting the stomach, so if you have a weak stomach or are vulnerable to acid reflux, the last thing you want to do is light the fire right before you lie down to rest.