What exactly are cold alleriges, and what can be done about them? I was recently diagnosed as having an allergy to the cold, and although the doctor tried to explain it to me, I didn't fully understand what it is. She said the only way to fight off the allergic reaction was to take an antihistamine before going outside. I was wondering if that was the only course of prevention, or if there was some other way.
Pam Smith - High School Student - Ontario, Canada
The immune system is an intricate, interconnected network designed to protect our bodies from the dangers of the world around us, especially the danger of invasion from infectious organisms of all types or from the civil war of our own cancerous cells turned against us. The immune system includes many types of white blood cells, lymph vessels, lymph nodes, a host of specific antibodies, cilia (hair cells for sweeping away unwanted particles), the spleen, tonsils, adenoids, and our largest organ — the flexible, complex barrier we call skin.
An allergy happens when part of the immune system goes awry. In its enthusiasm to protect us, the response by the immune system is sometimes so exuberant that it is worse than whatever precipitated it. People can develop allergies to a wide variety of things, including pollen, dust, animal dander, foods, and viruses. Some individuals have an allergic response to being in cold air or water.
This allergic response can take several forms, from rashes to wheezing – and then some! The main symptoms might be on the skin, in the blood, in the urine, in the nose or in the chest. Cold allergies can even cause generalized fatigue and decreased ability to learn.
Some people develop hives on the skin when they encounter cold temperatures. This condition, called cold urticaria, is the most common type of hives caused by a physical condition. The hives are produced by a rapid release of histamine brought about by IgE antibodies and eosinophils (a type of white blood cell often involved in allergic reactions) in response to the cold. Rapid cooling, as from the evaporation when one gets out of a swimming pool, can trigger cold urticaria even on a warm day. For people with cold urticaria, swimming in very cold water is quite dangerous, sometimes even causing death.
Treatment of cold urticaria involves avoiding the cold, when possible, and taking antihistamines. The antihistamines are best taken before exposure to cold temperatures to block some of the histamine release. Many of the over-the-counter antihistamines interfere with learning. I recommend a nonsedating drug, such as loratadine (Claritin) or cetirizine (Zyrtec).
Sometimes cold urticaria is a symptom of another problem, such as cryofibrinogenemia, cryoglobulinemia, or syphilis. Even when it is not, you can develop cold urticaria after receiving a blood transfusion from someone who has it. Most people don’t know that allergies can be transmitted in transfusions, but they can (Nelson Textbook of Pediatrics, WB Saunders, 2000)! For some people, cold urticaria is a lifelong condition; for others, it is temporary — only during and after an infection, such as mycoplasma or mononucleosis.
Both mononucleosis and mycoplasma infections can produce another type of cold allergy in the blood. Following these and a variety of other viral infections, exposure to the cold can cause anemia from allergic bursting of some of the red blood cells. Anemia can result in fatigue and other symptoms, including decreased ability to learn.
Paroxysmal cold hemoglobinuria is another specific type of cold allergy, often associated with syphilis, in which cold temperatures make the urine turn red with blood. These people should avoid being chilled until the effects of the underlying infection have ended.
Breathing cold air can also trigger nasal congestion and wheezing. Sometimes this is a purely physical effect. This happens in two ways.
First, cold air affects an important defense mechanism called mucus transport. The entire respiratory system is coated with a very thin mucous blanket. Cold air stimulates an increase in mucus production, but mucus (like other substances), becomes thicker in colder temperatures.
The second area where cold air physically affects respiratory health is in the nose tissue. The hardy nose is a remarkable organ designed to condition inhaled air to protect the delicate internal structures. When breathing through the nose, you may breathe in air at 40 or 100 degrees Fahrenheit, but within a quarter of a second, the air temperature is quickly brought to 98.6. Many tiny blood vessels, known as capillaries, bring about this temperature exchange. When a person breathes cold air, the tissues lining the nose swell as the capillaries dilate, bringing warm blood to heat the cool air. Swollen capillaries in the nose are the cause of nasal congestion (nasal congestion is backed-up blood, not increased mucus). In addition to the congestion, the mucus in the nose, as we’ve said, increases and becomes thicker. This happens more in some people than in others. Thus cold air, by itself, can produce both nasal congestion and stuffiness. These can be treated with decongestants and/or antihistamines.
Sometimes the runny nose, congestion, and/or wheezing are a true allergic response to cold temperatures. If this is the case, preventive medicines such as cromolyn (Nasalcrom) or fluticasone (Flonase) can work well for the nose, and cromolyn (Intal), nedocromil (Tilade), fluticasone (Flovent) or the like, can work well to prevent wheezing. A variety of natural remedies have also been proven to help prevent these types of allergies, including quercetin/vitamin C, stinging nettle, saline nose drops, saline eye drops, and a nightly massage.
The most important step in treating allergies is to identify what triggers them. You are on your way, Pam, with the observation that cold causes your symptoms. Now that you know this, you can work with you doctor to find the best combination of treatments to keep your allergic response in check and allow your immune system to get on with more important business.