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.

Semaglutide (sold as Ozempic, Wegovy and Rybelsus) was initially developed to treat diabetes. It works by stimulating the production of insulin to keep blood sugar levels in check.

This type of drug is increasingly being prescribed for weight loss, despite the fact it was initially approved for another purpose. Recently, there has been growing interest in another possible use: to treat addiction.

Anecdotal reports from patients taking semaglutide for weight loss suggest it reduces their appetite and craving for food, but surprisingly, it also may reduce their desire to drink alcohol, smoke cigarettes or take other drugs.

But does the research evidence back this up?

Animal studies show positive results

Semaglutide works on glucagon-like peptide-1 receptors and is known as a “GLP-1 agonist”.

Animal studies in rodents and monkeys have been overwhelmingly positive. Studies suggest GLP-1 agonists can reduce drug consumption and the rewarding value of drugs, including alcohol, nicotine, cocaine and opioids.

Out team has reviewed the evidence and found more than 30 different pre-clinical studies have been conducted. The majority show positive results in reducing drug and alcohol consumption or cravings. More than half of these studies focus specifically on alcohol use.

However, translating research evidence from animal models to people living with addiction is challenging. Although these results are promising, it’s still too early to tell if it will be safe and effective in humans with alcohol use disorder, nicotine addiction or another drug dependence.

What about research in humans?

Research findings are mixed in human studies.

Only one large randomised controlled trial has been conducted so far on alcohol. This study of 127 people found no difference between exenatide (a GLP-1 agonist) and placebo (a sham treatment) in reducing alcohol use or heavy drinking over 26 weeks.

In fact, everyone in the study reduced their drinking, both people on active medication and in the placebo group.

However, the authors conducted further analyses to examine changes in drinking in relation to weight. They found there was a reduction in drinking for people who had both alcohol use problems and obesity.

For people who started at a normal weight (BMI less than 30), despite initial reductions in drinking, they observed a rebound increase in levels of heavy drinking after four weeks of medication, with an overall increase in heavy drinking days relative to those who took the placebo.

There were no differences between groups for other measures of drinking, such as cravings.

In another 12-week trial, researchers found the GLP-1 agonist dulaglutide did not help to reduce smoking.

However, people receiving GLP-1 agonist dulaglutide drank 29% less alcohol than those on the placebo. Over 90% of people in this study also had obesity.

Smaller studies have looked at GLP-1 agonists short-term for cocaine and opioids, with mixed results.

There are currently many other clinical studies of GLP-1 agonists and alcohol and other addictive disorders underway.

While we await findings from bigger studies, it’s difficult to interpret the conflicting results. These differences in treatment response may come from individual differences that affect addiction, including physical and mental health problems.

Larger studies in broader populations of people will tell us more about whether GLP-1 agonists will work for addiction, and if so, for whom.

How might these drugs work for addiction?

The exact way GLP-1 agonists act are not yet well understood, however in addition to reducing consumption (of food or drugs), they also may reduce cravings.

Animal studies show GLP-1 agonists reduce craving for cocaine and opioids.

This may involve a key are of the brain reward circuit, the ventral striatum, with experimenters showing if they directly administer GLP-1 agonists into this region, rats show reduced “craving” for oxycodone or cocaine, possibly through reducing drug-induced dopamine release.

Using human brain imaging, experimenters can elicit craving by showing images (cues) associated with alcohol. The GLP-1 agonist exenatide reduced brain activity in response to an alcohol cue. Researchers saw reduced brain activity in the ventral striatum and septal areas of the brain, which connect to regions that regulate emotion, like the amygdala.

In studies in humans, it remains unclear whether GLP-1 agonists act directly to reduce cravings for alcohol or other drugs. This needs to be directly assessed in future research, alongside any reductions in use.

Are these drugs safe to use for addiction?

Overall, GLP-1 agonists have been shown to be relatively safe in healthy adults, and in people with diabetes or obesity. However side effects do include nausea, digestive troubles and headaches.

And while some people are OK with losing weight as a side effect, others aren’t. If someone is already underweight, for example, this drug might not be suitable for them.

In addition, very few studies have been conducted in people with addictive disorders. Yet some side effects may be more of an issue in people with addiction. Recent research, for instance, points to a rare risk of pancreatitis associated with GLP-1 agonists, and people with alcohol use problems already have a higher risk of this disorder.

Other drugs treatments are currently available

Although emerging research on GLP-1 agonists for addiction is an exciting development, much more research needs to be done to know the risks and benefits of these GLP-1 agonists for people living with addiction.

In the meantime, existing effective medications for addiction remain under-prescribed. Only about 3% of Australians with alcohol dependence, for example, are prescribed medication treatments such as like naltrexone, acamprosate or disulfiram. We need to ensure current medication treatments are accessible and health providers know how to prescribe them.

Continued innovation in addiction treatment is also essential. Our team is leading research towards other individualised and effective medications for alcohol dependence, while others are investigating treatments for nicotine addiction and other drug dependence.

Read the other articles in The Conversation’s Ozempic series here.

Shalini Arunogiri, Addiction Psychiatrist, Associate Professor, Monash University; Leigh Walker, , Florey Institute of Neuroscience and Mental Health, and Roberta Anversa, , The University of Melbourne

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