Hayfever, Antihistamines and Health: Managing Hayfever the Smart Way

Summer is great. Unless you have hay fever, in which case it involves a lot of sneezing, itchy eyes, and wondering whether you'll ever feel normal again.

Hay fever, or allergic rhinitis, is an inflammatory reaction to pollen. For many people, antihistamines are the first line of defense. They work well. But if you're taking them daily through peak pollen season, it's worth understanding how they work, what the side effects are, and whether there's anything else you can do alongside them.

What are antihistamines and how do they work?

Antihistamines block histamine, a chemical your body releases during an allergic reaction. Histamine tells your immune system to ramp up its defenses, causing blood vessels to expand and triggering the familiar symptoms: sneezing, itching, watery eyes, and swelling.

When pollen is the trigger, your body mistakes it for a threat. Antihistamines interrupt that chain reaction, which is why they can bring relief within an hour or two.

First-generation vs. second-generation antihistamines

There are two main categories:

First-generation antihistamines (such as diphenhydramine and hydroxyzine) cross the blood-brain barrier, which is why they tend to make you drowsy. They come as tablets, liquids, and creams.

Second-generation antihistamines (cetirizine, loratadine, fexofenadine) cross the blood-brain barrier to a much lesser degree. They're less likely to cause sleepiness and are the more commonly recommended option for daytime use.

Short-term side effects: what to expect

Even when taken occasionally, antihistamines can cause side effects, particularly first-generation versions. Common ones include drowsiness, dry mouth, blurred vision, constipation, and difficulty urinating. At higher doses, first-generation antihistamines can cause dizziness and tinnitus.

Second-generation antihistamines are significantly less likely to cause drowsiness or dry mouth.

Who should exercise caution?

• Older adults face a higher risk of falls and confusion with first-generation antihistamines
• People who are pregnant or breastfeeding
• Young children
• People with underlying health conditions, as certain antihistamines can worsen existing symptoms

If you fall into any of these groups, speak to your pharmacist or healthcare provider before starting antihistamines.

Long-term and daily use: is it a problem?

If you're taking antihistamines every day through hay fever season, you might wonder whether that's doing you any harm in the long run. The honest answer is that the evidence on long-term effects is mixed. Research is ongoing, and it's worth reviewing your treatment with a healthcare provider if you're taking them continuously and finding they're becoming less effective over time.

Some people notice their body appears to get used to antihistamines, with symptoms feeling less controlled after extended use. If that happens, it's a good reason to check in with your healthcare provider rather than simply increasing the dose.

Practical tips for managing side effects

A few simple habits can help:

• Stick to the lowest effective dose
• Drink plenty of water to reduce dry mouth
• Take the antihistamine closer to bedtime if it makes you drowsy
• Look for packaging that clearly says "non-drowsy" if daytime alertness matters to you
• If you notice confusion, worsening mood, memory changes, or difficulty urinating, talk to a healthcare provider

Can nutrition help with hay fever symptoms?

Antihistamines treat the symptoms. But certain foods have anti-inflammatory properties that may help reduce their severity. The evidence varies in strength, so treat these as supportive additions to your existing treatment, not replacements for it.

Fatty fish: Salmon, mackerel, and sardines are rich in omega-3 fatty acids, particularly EPA and DHA. Research suggests these help produce anti-inflammatory compounds that may reduce the severity of allergic conditions like hay fever.

Citrus fruits: Oranges, grapefruit, and lemons are high in vitamin C, which has antioxidant properties and may help lower histamine levels in the body.

Garlic and onions: Both contain quercetin, a flavonoid with natural antihistamine properties. Studies suggest quercetin-rich foods may help reduce the severity of allergic reactions when incorporated into your regular diet.

Local honey: Contains small traces of local pollen. There's limited evidence behind it, but some research suggests regular consumption during the off-season might help the immune system gradually adjust to local pollen. Worth a try, if not a cure.

Probiotic-rich foods: Yogurt, kefir, kimchi, sauerkraut, and miso support gut health and immune function. Research suggests that probiotics may help ease allergy symptoms over time.

These foods work best as part of a consistently balanced diet, not as a last-minute hay fever hack. If you're considering significant dietary changes, speak to a registered dietitian or healthcare provider first.

Read more: Can nutrition help with hay fever?

Key takeaways

• First-generation antihistamines are effective but more likely to cause drowsiness and other side effects
• Second-generation antihistamines are the better option for most people during the day
• If you're taking antihistamines daily over a long period, review your treatment with a healthcare provider, especially if they seem to be losing effectiveness
• Certain foods, including fatty fish, quercetin-rich vegetables, and probiotics, may offer additional support alongside conventional treatment
• If you're pregnant, older, or have an existing health condition, check with a pharmacist or healthcare provider before starting any antihistamine