Allergies happen when your immune system overreacts to a normally harmless substance like dust or pollen. Hay fever, hives and anaphylaxis are all types of allergic reactions.

Many of those affected reach quickly for antihistamines to treat mild to moderate allergies (though adrenaline, not antihistamines, should always be used to treat anaphylaxis).

If you’re using oral antihistamines very often, you might have wondered if it’s OK to keep relying on antihistamines to control symptoms of allergies. The good news is there’s no research evidence to suggest regular, long-term use of modern antihistamines is a problem.

But while they’re good at targeting the early symptoms of a mild to moderate allergic reaction (sneezing, for example), oral antihistamines aren’t as effective as steroid nose sprays for managing hay fever. This is because nasal steroid sprays target the underlying inflammation of hay fever, not just the symptoms.

Here are the top six antihistamines myths – busted.

Myth 1. Oral antihistamines are the best way to control hay fever symptoms

Wrong. In fact, the recommended first line medical treatment for most patients with moderate to severe hay fever is intranasal steroids. This might include steroid nose sprays (ask your doctor or pharmacist if you’d like to know more).

Studies have shown intranasal steroids relieve hay fever symptoms better than antihistamine tablets or syrups.

To be effective, nasal steroids need to be used regularly, and importantly, with the correct technique.

In Australia, you can buy intranasal steroids without a doctor’s script at your pharmacy. They work well to relieve a blocked nose and itchy, watery eyes, as well as improve chronic nasal blockage (however, antihistamine tablets or syrups do not improve chronic nasal blockage).

Some newer nose sprays contain both steroids and antihistamines. These can provide more rapid and comprehensive relief from hay fever symptoms than just oral antihistamines or intranasal steroids alone. But patients need to keep using them regularly for between two and four weeks to yield the maximum effect.

For people with seasonal allergic rhinitis (hayfever), it may be best to start using intranasal steroids a few weeks before the pollen season in your regions hits. Taking an antihistamine tablet as well can help.

Antihistamine eye drops work better than oral antihistamines to relieve acutely itchy eyes (allergic conjunctivitis).

Myth 2. My body will ‘get used to’ antihistamines

Some believe this myth so strongly they may switch antihistamines. But there’s no scientific reason to swap antihistamines if the one you’re using is working for you. Studies show antihistamines continue to work even after six months of sustained use.

Myth 3. Long-term antihistamine use is dangerous

There are two main types of antihistamines – first-generation and second-generation.

First-generation antihistamines, such as chlorphenamine or promethazine, are short-acting. Side effects include drowsiness, dry mouth and blurred vision. You shouldn’t drive or operate machinery if you are taking them, or mix them with alcohol or other medications.

Most doctors no longer recommend first-generation antihistamines. The risks outweigh the benefits.

The newer second-generation antihistamines, such as cetirizine, fexofenadine, or loratadine, have been extensively studied in clinical trials. They are generally non-sedating and have very few side effects. Interactions with other medications appear to be uncommon and they don’t interact badly with alcohol. They are longer acting, so can be taken once a day.

Although rare, some side effects (such as photosensitivity or stomach upset) can happen. At higher doses, cetirizine can make some people feel drowsy. However, research conducted over a period of six months showed taking second-generation antihistamines is safe and effective. Talk to your doctor or pharmacist if you’re concerned.

Myth 4. Antihistamines aren’t safe for children or pregnant people

As long as it’s the second-generation antihistamine, it’s fine. You can buy child versions of second-generation antihistamines as syrups for kids under 12.

Though still used, some studies have shown certain first-generation antihistamines can impair childrens’ ability to learn and retain information.

Studies on second-generation antihistamines for children have found them to be safer and better than the first-generation drugs. They may even improve academic performance (perhaps by allowing kids who would otherwise be distracted by their allergy symptoms to focus). There’s no good evidence they stop working in children, even after long-term use.

For all these reasons, doctors say it’s better for children to use second-generation than first-generation antihistimines.

What about using antihistimines while you’re pregnant? One meta analysis of combined study data including over 200,000 women found no increase in fetal abnormalities.

Many doctors recommend the second-generation antihistamines loratadine or cetirizine for pregnant people. They have not been associated with any adverse pregnancy outcomes. Both can be used during breastfeeding, too.

Myth 5. It is unsafe to use higher than the recommended dose of antihistamines

Higher than standard doses of antihistamines can be safely used over extended periods of time for adults, if required.

But speak to your doctor first. These higher doses are generally recommended for a skin condition called chronic urticaria (a kind of chronic hives).

Myth 6. You can use antihistamines instead of adrenaline for anaphylaxis

No. Adrenaline (delivered via an epipen, for example) is always the first choice. Antihistamines don’t work fast enough, nor address all the problems caused by anaphylaxis.

Antihistamines may be used later on to calm any hives and itching, once the very serious and acute phase of anaphylaxis has been resolved.

In general, oral antihistamines are not the best treatment to control hay fever – you’re better off with steroid nose sprays. That said, second-generation oral antihistamines can be used to treat mild to moderate allergy symptoms safely on a regular basis over the long term.

Janet Davies, Respiratory Allergy Stream Co-chair, National Allergy Centre of Excellence; Professor and Head, Allergy Research Group, Queensland University of Technology; Connie Katelaris, Professor of Immunology and Allergy, Western Sydney University, and Joy Lee, Respiratory Allergy Stream member, National Allergy Centre of Excellence; Associate Professor, School of Public Health and Preventive Medicine, Monash University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Are you one of these people who loathes spending time outdoors at dusk as the weather warms and mosquitoes start biting?

Female mosquitoes need blood to develop their eggs. Even though they take a tiny amount of our blood, they can leave us with itchy red lumps that can last days. And sometimes something worse.

So why does our body react and itch after being bitten by a mosquito? And why are some people more affected than others?

What happens when a mosquito bites?

Mosquitoes are attracted to warm blooded animals, including us. They’re attracted to the carbon dioxide we exhale, our body temperatures and, most importantly, the smell of our skin.

The chemical cocktail of odours from bacteria and sweat on our skin sends out a signal to hungry mosquitoes.

Some people’s skin smells more appealing to mosquitoes, and they’re more likely to be bitten than others.

Once the mosquito has made its way to your skin, things get a little gross.

The mosquito pierces your skin with their “proboscis”, their feeding mouth part. But the proboscis isn’t a single, straight, needle-like tube. There are multiple tubes, some designed for sucking and some for spitting.

Once their mouth parts have been inserted into your skin, the mosquito will inject some saliva. This contains a mix of chemicals that gets the blood flowing better.

There has even been a suggestion that future medicines could be inspired by the anti-blood clotting properties of mosquito saliva.

It’s not the stabbing of our skin by the mosquito’s mouth parts that hurts, it’s the mozzie spit our bodies don’t like.

Are some people allergic to mosquito spit?

Once a mosquito has injected their saliva into our skin, a variety of reactions can follow. For the lucky few, nothing much happens at all.

For most people, and irrespective of the type of mosquito biting, there is some kind of reaction. Typically there is redness and swelling of the skin that appears within a few hours, but often more quickly, after just a few minutes.

Occasionally, the reaction can cause pain or discomfort. Then comes the itchiness.

Some people do suffer severe reactions to mosquito bites. It’s a condition often referred to as “skeeter syndrome” and is an allergic reaction caused by the protein in the mosquito’s saliva. This can cause large areas of swelling, blistering and fever.

The chemistry of mosquito spit hasn’t really been well studied. But it has been shown that, for those who do suffer allergic reactions to their bites, the reactions may differ depending on the type of mosquito biting.

We all probably get more tolerant of mosquito bites as we get older. Young children are certainly more likely to suffer more following mosquito bites. But as we get older, the reactions are less severe and may pass quickly without too much notice.

How best to treat the bites?

Research into treating bites has yet to provide a single easy solution.

There are many myths and home remedies about what works. But there is little scientific evidence supporting their use.

The best way to treat mosquito bites is by applying a cold pack to reduce swelling and to keep the skin clean to avoid any secondary infections. Antiseptic creams and lotions may also help.

There is some evidence that heat may alleviate some of the discomfort.

It’s particularly tough to keep young children from scratching at the bite and breaking the skin. This can form a nasty scab that may end up being worse than the bite itself.

Applying an anti-itch cream may help. If the reactions are severe, antihistamine medications may be required.

To save the scratching, stop the bites

Of course, it’s better not to be bitten by mosquitoes in the first place. Topical insect repellents are a safe, effective and affordable way to reduce mosquito bites.

Covering up with loose fitted long sleeved shirts, long pants and covered shoes also provides a physical barrier.

Mosquito coils and other devices can also assist, but should not be entirely relied on to stop bites.

There’s another important reason to avoid mosquito bites: millions of people around the world suffer from mosquito-borne diseases. More than half a million people die from malaria each year.

In Australia, Ross River virus infects more than 5,000 people every year. And in recent years, there have been cases of serious illnesses caused by Japanese encephalitis and Murray Valley encephalitis viruses.

Cameron Webb, Clinical Associate Professor and Principal Hospital Scientist, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.