Pillows should generally be replaced every 1 to 2 years to ensure proper support, hygiene, and comfort. Different types of pillows have varying lifespans, with synthetic and memory foam pillows typically lasting about 2 years, while latex pillows can last up to 5 years. Natural pillows such as feather or down usually need changing every 1 to 2 years as well. Signs that indicate it's time to replace a pillow include loss of shape and support, flattening, lumpy texture, permanent odors, stains, or causing neck pain. Additionally, pillows can harbor dust, mold, and bacteria if kept too long, potentially affecting allergies and sleep quality.