An allergic reaction, inflammation, an injury to the lip or a bacterial or viral infection can cause swollen lips in the morning, according to BootsWebMD. Individuals with an underlying medical condition or disease may also experience swollen lips as a side effect of the ailment or medication.
Reactions to bee or wasp stings and pollen within the air cause lips to swell in the morning for some patients, as BootsWebMD explains. Overexertion during exercise, exposure to latex and airborne chemicals, or reactions to certain medications may cause side effects such as swollen lips.
Angioedema, a condition that causes the lips, throat, tongue and area around the eye to swell, can cause swollen lips in the morning, according to About.com. Angioedema also causes hives to form on the skin or reddish, irritated skin on the face and body.
Allergic reactions commonly cause swollen lips, as noted by BootsWebMD. People who have contact with an allergen, such as a lip care product, certain foods or pet dander, may experience a reaction that causes lips to swell at any time of the day. When an allergic reaction occurs, the immune system reacts with swelling and inflammation to fight the harmful agent or bacteria.