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Stinging nettle seeds germinate in the spring. Underground stems, or rhizome fragments, can also develop into mature plants under favorable conditions. Often large clumps of plants grow from rhizomes in uncultivated areas. The flowers bloom from March to September.
As a perennial plant, stinging nettle may live for several years regrowing from rhizomes. Both burning and stinging nettle are aptly named. Their leaves and stems are covered with long, fine to bristly hairs that can irritate and blister skin when handled. When human skin comes into contact with a leaf or stem, it often rapidly develops reddish patches accompanied by itching and burning.
Frequently, a prolonged tingling sensation may persist on the affected skin for more than 12 hours, even after visible symptoms have faded. The prickly hairs of both burning and stinging nettle consist of a minute tubelike structure that has a hard round bulb at the tip and a softer vessel at the base. This bulb breaks off after contact with skin and exposes a needlelike point.
When the tip contacts and penetrates the skin, it puts pressure on the basal vessel and results in the needlelike injection of irritating substances under the skin. The contents of the structures are not fully known, but have been found to contain active concentrations of the neurotransmitter chemicals acetylcholine and histamine.
Unlike poison oak, which causes a red, itchy, weepy reaction called allergic dermatitis in only a portion of the population, the nettles affect everyone equally. This is known as irritant dermatitis.
Along the coast, burning nettle is particularly problematic because it grows year-round. Stinging nettle plants can become a nuisance for farmers when large stands block irrigation waterways. Stinging nettle prefers moist areas in wildlands, such as areas surrounding creeks or rivers. If these sites occur along hiking trails, plants can be a nuisance or even a health hazard to visitors. Burning and stinging nettles growing in the home garden and landscape are best controlled using cultural and mechanical methods.
Burning and stinging nettles can be controlled by removing plants by hand. If you're an outdoorsy person who takes the occasional hike or camping trip in the summertime, here's what experts want you to know about stinging nettle rashes—including the most common symptoms and how best to treat the itch and irritation.
So, stinging nettle rashes happen when a person comes into contact with a stinging nettle plant, technically known as Urtica dioica.
Stinging nettle plants sometimes just called stinging nettles are normally found near riverbanks and in areas of farmland, according to the New York State Department of Environmental Conservation DEC. The plants can grow up to 8 feet tall and have thin, dark green leaves with a tapered tip.
The plants actually have two types of hairs on them—both ordinary and those that sting, the DEC says. The stinging hairs are longer, about 1 millimeter in length, and stick out aggressively on the stems and leaves. It's those hairs that cause a stinging nettle rash. Per the DEC, when you come into contact with one of the stinging hairs, a piece breaks off and subjects your skin to "dose of histamine, acetylcholine, serotonin and formic acid.
What causes urticaria? Histamine is released for many reasons, including: an allergic reaction — such as a food allergy or a reaction to an insect bite or sting cold or heat exposure infection — such as a cold certain medications — such as non-steroidal anti-inflammatory drugs NSAIDs or antibiotics However, in many cases of urticaria, no obvious cause can be found.
Certain triggers may also make the symptoms worse. These include: drinking alcohol or caffeine emotional stress warm temperature Read more about the causes of urticaria. Diagnosing urticaria Your GP will usually be able to diagnose urticaria by examining the rash. Treating urticaria In many cases, treatment isn't needed for urticaria, because the rash often gets better within a few days.
Complications of urticaria Around a quarter of people with acute urticaria and half of people with chronic urticaria also develop angioedema, which is a deeper swelling of tissues.
Angioedema Angioedema is swelling in the deeper layers of a person's skin. The symptoms of angioedema can affect any part of the body, but usually affect the: eyes lips genitals hands feet Medication such as antihistamines and short courses of oral corticosteroids tablets can be used to relieve the swelling.
Emotional impact Living with any long-term condition can be difficult. It also found that one in seven people with chronic urticaria had some sort of psychological or emotional problem, such as: stress anxiety depression See your GP if your urticaria is getting you down.
Anaphylaxis Urticaria can be one of the first symptoms of a severe allergic reaction known as anaphylaxis. Other symptoms of anaphylaxis include: swollen eyes, lips, hands and feet feeling lightheaded or faint narrowing of the airways, which can cause wheezing and breathing difficulties abdominal pain, nausea and vomiting collapsing and becoming unconsciousness Anaphylaxis should always be treated as a medical emergency.
Who can get it Urticaria occurs when histamine and other chemicals are released from under the skin's surface, causing the tissues to swell. Short-term acute urticaria The triggers of acute urticaria are unknown in around half of all cases. Recognised triggers include: a food allergy — to foods such as peanuts, shellfish, eggs and cheese an allergic reaction — to environmental factors such as pollen, dust mites or chemicals an allergic reaction to latex — which can be a common problem in healthcare workers infections — which can range from relatively trivial, such as a cold , to very serious, such as HIV insect bites and stings emotional stress certain medications that can cause urticaria as a side effect — including antibiotics , non-steroidal anti-inflammatory drugs NSAIDs and aspirin physical triggers — such as pressure to the skin, changes in temperature, sunlight, exercise or water Long-term chronic urticaria Chronic urticaria may occur when the body's immune system attacks its own tissues.
About a third to half of all chronic cases of urticaria are thought to be autoimmune related. It's not known why autoimmune urticaria develops, although it can sometimes occur in combination with other autoimmune conditions, such as: rheumatoid arthritis — when the immune system attacks the joints lupus — when the immune system attacks the joints and skin, and people usually feel tired all the time Chronic urticaria can also be linked to other chronic illnesses and infections, such as: viral hepatitis liver infection intestinal parasites an underactive thyroid gland hypothyroidism an overactive thyroid gland hyperthyroidism Chronic urticaria tends to come and go.
Triggers sometimes include: stress alcohol caffeine warm temperatures prolonged pressure on the skin — this can happen by wearing tight clothing medications — such as NSAIDs, and the painkiller codeine certain food additives — such as salicylates, which are found in tomatoes, orange juice and tea insect bites and stings exposure to heat, cold, pressure or water ACE inhibitors that are often used to treat high blood pressure hypertension can be linked to deeper swellings of angioedema.
Diagnosis Urticaria can usually be diagnosed by examining the distinctive red rash. Short-term acute urticaria Your GP can usually diagnose acute urticaria by examining the rash.
They'll also ask you some questions to find out what triggered your symptoms, including: when and where the rash began what you had to eat just before it began and details of your usual diet if you started taking any new medication just before your symptoms began if you live or work in an environment where you come into contact with possible triggers — such as pets, chemicals or latex gloves if you were stung or bitten by an insect just before your symptoms started your current state of health and if you've had any recent infections if you've recently travelled to a foreign country and if so, where if there's a history of urticaria in your family In around half of all cases of acute urticaria, a cause can't be identified.
Long-term chronic urticaria If your urticaria lasts for more than six weeks, it's very unlikely to be caused by an allergy, so allergy tests aren't usually recommended. However, your GP should ask about anything that makes your urticaria worse, such as: any medicines you're taking your alcohol and caffeine consumption your stress levels You may also be referred for a number of tests to find out if there's an underlying cause of your chronic urticaria.
These tests may include: a full blood count test FBC — which can identify anaemia tests to determine the levels of antibodies in your blood a stool sample — which can identify intestinal parasites an erythrocyte sedimentation rate ESR test — which can help to identify problems with your immune system thyroid function tests — which can be used to check for an underactive thyroid gland hypothyroidism or an overactive thyroid gland hyperthyroidism liver function tests — which can be used to check if you have any problems with your liver.
Treatment Most cases of urticaria don't need treatment, because the symptoms are usually mild and often get better within a few days. Short-term acute urticaria If your symptoms are troublesome or persistent, antihistamines are available over the counter from pharmacies.
Antihistamines Antihistamines block the effects of histamine, helping to stop the itchiness and reduce the rash. Examples of antihistamines include: cetirizine fexofenadine loratadine For most people, modern antihistamines don't cause drowsiness, although there are some exceptions. Corticosteroid tablets You may be prescribed a short course of high-dose corticosteroid tablets, such as prednisolone, if your symptoms are severe.
Taking steroid tablets on a long-term basis isn't usually recommended, because it can lead to a wide range of side effects and complications, such as: high blood pressure hypertension glaucoma cataracts diabetes or it can make existing diabetes worse Long-term chronic urticaria Treatment for chronic urticaria involves trying to control your symptoms and avoiding any triggers that make them worse.
Antihistamines Chronic urticaria is treated with antihistamines. Menthol cream Menthol cream can be used as an alternative or in addition to antihistamines because it helps to relieve itchiness. Corticosteroid tablets Occasionally, more serious episodes of urticaria can be treated with short doses of corticosteroid tablets, such as prednisolone. Possible side effects of corticosteroid tablets include: increased appetite and weight gain mood change difficulty sleeping insomnia Long-term use of corticosteroids for chronic urticaria isn't recommended for the reasons mentioned above.
H2 antihistamines The type of antihistamines you can get from the pharmacist are known as H1 antihistamines. Side effects of H2 antihistamines are uncommon, but include: headache diarrhoea dizziness Don't drive or use tools or machinery if you feel dizzy after taking a H2 antihistamine. Leukotriene receptor antagonists Leukotriene receptor antagonists are a type of medication that can help to reduce redness and swelling of the skin.
Ciclosporin In around two-thirds of cases, a powerful medication called ciclosporin has proved effective in treating urticaria. Side effects of ciclosporin include: high blood pressure hypertension kidney problems increased levels of blood cholesterol headaches involuntary shaking tremors increased vulnerability to infection, particularly chest infections , urinary tract infections UTIs and a type of viral infection known as cytomegalovirus There are also a number of other side effects that can occur when taking ciclosporin, and you should discuss these thoroughly with your doctor before starting.
Omaluzimab For urticaria that hasn't responded to antihistamines, there are newer medications becoming available, such as omalizumab. Diet There's some uncertainty over the role of diet in people with long-term urticaria. The Allergy UK website has more information on: vasoactive amines salicylates Avoiding or cutting down on foods that contain these chemicals may improve your symptoms.
Avoiding triggers If you know what triggers your urticaria or makes it worse, avoiding the trigger may keep your symptoms under control.
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