Lips can swell for many reasons, one of which is allergic reaction. Swollen lips from allergies usually start with a tingling in the lips, followed by the sensation of feeling the lips steadily swell over the next few hours. The swelling may remain at its worst for several hours before gradually easing, disappearing altogether after perhaps 12-24 hours.
A range of allergens can cause swollen lips, including from food, insect stings and bites, medications, contact with certain products, dust, pollen, infectious diseases, bacteria, pollution, and contaminants. A food allergy is the most common type of allergy and is where the immune system is upset after a particular food. Various foods can cause the lips to swell in people susceptible to allergies, although the most common is probably shellfish. An insect sting by a bee, wasp, hornet or ant, or by a biting insect such as a mosquito, bug or tic, to the lips or nearby areas can set up an allergic reaction and cause swollen lips. Almost any medication can bring on an allergic reaction, although antibiotics, penicillin, and aspirin are noted for producing allergies. This usually involves skin rashes or hives but can also result in swollen lips, tongue and face.
Allergic reactions such as swollen lips can occur by coming into contact with other allergens. This can include not only things like dust, pollen, animal fur, and grass, but also blowing up a balloon, touching your face with a rubber glove, contact with other latex products, and after a visit to the dentist or the hairdresser. Lip swelling can result from contact with mattresses or pillows if they are made of a material that causes local irritation. People who sleep on their sides or front are more at risk. Any allergic reaction, including lip swelling, can be hereditary too.
Swollen lips are the most common symptom of a condition called angioedema, which is usually the result of an allergy. "Angio" means blood vessels and "edema" is swelling. The blood vessels leak fluid which causes a local build up in the tissues under the skin resulting in swelling. The condition can also cause swelling in the hands and elsewhere. Urticaria may develop too.
The best way to cope with swollen lips is to take antihistamines and try to isolate the cause. If you suspect the problem is food, record what you eat and any reactions in a diary. Determine the suspect foods and avoid them one at a time until you isolate the culprit. Look at food labels in the supermarket to make sure you're not buying products containing your allergy. Skin prick and blood tests are always options, as is seeing your doctor or dietitian.
A long time ago, I suffered periodic lip swelling for many years. My first episode was about a month after my wife and I soaked our feet in water with cayenne pepper. It was supposed to get rid of colds. It did that alright. I didn't have a proper cold for perhaps a decade. Instead, my lips would swell up to several times their normal size. It probably didn't help that I left my feet in the solution for 20-30 minutes as it was only supposed to be for a few minutes. My wife couldn't leave her feet in it at all as she felt that it was burning her feet.
The first time I had swollen lips was the night after eating a warm, mildly spicy seafood dish at a work lunch one day. I put it down to the seafood, but in hindsight, the underlying cause was probably the cayenne pepper a few weeks earlier, and the seafood dish may have been the catalyst. I soon had more episodes. Before long, hardly a week went past when my lips didn't swell. It was usually combined with urticaria, which could be quite itchy and could appear anywhere on my body, as well as on the backside and thighs, like I was burning from the inside.
My lips weren't the only thing to swell. I also suffered swelling to the tongue, nose, eyes, lower arms, hands, fingers, thighs, and legs, but never to the throat, so I'm lucky in that regard. It made me feel lethargic and I sometimes had to take a day off work with it, but never more than one day at a time as the symptoms completely disappeared within a day. We were busy and often ate Chinese takeaway for tea. I had a liking for honey prawns and they often comprised my tea 3-4 times a week. This wouldn't have helped my allergy, so I stopped eating them but my lips kept swelling up.
I went to several specialist doctors but none seemed to have the answer. They put me on courses of antibiotics, cortisone and antihistamines. These suppressed the symptoms but didn't eliminate them. I had blood tests, which didn't show any problem. I also had skin prick tests for allergies and this didn't find anything either. I was skin tested for 89 substances. On a scale of 0-5, with 0 being no reaction and 5 being a severe reaction, I rated 0 for about 75 substances and 1 for the rest.
I was getting swollen lips from pepper, dust, oil on sultanas, and petroleum products. My wife used to wear petroleum jelly on her lips if they were a bit dry. One night, I kissed her goodnight and immediately felt a tingling and hardening of the lips. Over the next few hours, I lay awake as my lips grew larger and larger. On other occasions, they started swelling in the early morning after I had lain on my side for several hours. This would have been an allergic reaction to the mattress or pillow. The swelling would start on the side of the lips that was resting on the bed. Gradually, the swelling became even across the lips. I also suffered neuralgia around the gums, and could be in a lot of pain. But I never had neuralgia and swollen lips together; it was one or the other.
Just as children often outgrow their allergies, I seemed to outgrow mine. Over the years, the severity of my lip swelling lessened and episodes became further apart. Improvement in diet probably helped too, although most of this came after my worst allergy years were behind me. My diet was never too dreadful anyway. These days, the lip swelling has gone, as has the neuralgia and the urticaria, and I've hardly had an episode of any of these things for perhaps a decade. I might have passed the allergy on to my nephew though. He has had slight to moderately swollen lips after eating a large number of fresh prawns. What I had was probably angioedema.