The onset of spring beckons seasonal allergic rhinitis, commonly known as hay fever. Allergens such as the pollen released from trees, grasses and weeds are carried in the air, triggering an immune system response.

In people with hay fever, the immune system overreacts, producing antibodies that attack the allergenic substance. While pollen isn’t harmful, the symptoms of allergic rhinitis can include sneezing, a blocked nose (nasal congestion) and irritated eyes (allergic conjunctivitis).

Hay fever

While hay fever will not directly affect your diabetes, allergy symptoms can leave you unwell and make it harder to manage your condition.

Tiredness caused by congestion or disrupted sleep means it can be challenging to keep track of your blood glucose levels, and you may not notice the signs of low blood sugar (hypoglycaemia) or high blood sugar (hyperglycaemia).

Prescription and over-the-counter medications can be taken to treat hay fever, including nasal sprays, eye drops and oral medications. However, most medicines available have side effects that impact blood glucose levels.

Symptoms of seasonal allergies

Common symptoms of hay fever include:

  • Sneezing
  • Runny or blocked nose
  • Itchy and watery eyes
  • Congested ears
  • Postnasal drip
  • Itchiness in the roof of your mouth or throat

Less common symptoms can also include:

  • Headache
  • Shortness of breath
  • Coughing

Symptoms range in severity and are often worse when there is a higher pollen count.

Treatments for allergies


These medications can stop allergy symptoms such as sneezing and allergic conjunctivitis and are typically available on prescription and over-the-counter.

While antihistamines will not directly affect your diabetes, some can cause drowsiness, making it harder to spot the symptoms of high and low blood glucose levels.

Some antihistamines are non-drowsy and might be a better option if you are concerned about monitoring your blood sugar.

Before taking any new medication, you should consult with your healthcare professional.


Available as oral medicines and nasal sprays, decongestants help to relieve a blocked nose by drying up the secretions in your nasal passages.

If you have diabetes, you should avoid decongestants containing phenylephrine and pseudoephedrine, as these can raise blood sugar levels and cause hyperglycaemia.

Decongestants can also raise heart rate and blood pressure, and you should discuss your options with your GP or pharmacist before taking them.

Steroids (Corticosteroids)

Corticosteroids are used to reduce and treat inflammation caused by hay fever. The most common type of steroid available to treat allergies is a nasal spray, but they can also come in the form of oral medications and eye drops.

Steroids can make the liver release more glucose and block the effect of insulin, causing insulin resistance. Both of these can be particularly dangerous for people with diabetes, causing hyperglycaemia due to the excess glucose in the blood.

If you are required to take any steroid treatments, you should regularly check your blood glucose levels, informing your doctor of any changes.

Due to its impact on blood glucose levels, long-term use of corticosteroids has also been known to trigger the development of type 2 diabetes, also known as drug-induced diabetes.

Avoiding allergies

Although it is not always possible to avoid the causes of seasonal allergic rhinitis, there are some preventative measures you can take, including:

  • Wearing sunglasses to keep pollen away from your eyes.
  • Wash off pollen from your skin and hair by taking a shower after being inside.
  • Remove excess moisture out of your home by using a dehumidifier, keeping it well-ventilated when possible.
  • Avoid going outside when the pollen forecast is predicted to be high.
  • Wash your bedding regularly, and consider using hypoallergenic bedding that is resistant to allergens.

How can I tell if I have a cold or hay fever?

Colds are caused by a virus and are contagious, while hay fever is an allergic reaction to pollen and is not contagious. Cold symptoms can occur any time although they are more common in colder months. Whereas hay fever symptoms align with pollen seasons and worsen when outdoors during high pollen counts. Symptoms may be different too. Colds symptoms include:

  • Sneezing
  • Coughing
  • Sore throat
  • Headaches
  • Possible fever
  • Loss of taste or smell

Symptoms typically last 1-2 weeks. For hay fever, symptoms can last for weeks or even months during pollen seasons. Observing patterns with when your symptoms occur can help indicate whether it’s hay fever or a cold. If in doubt, consult your healthcare team.

Get our free newsletters

Stay up to date with the latest news, research and breakthroughs.

You May Also Like

Diabetic Ketoacidosis (DKA)

Diabetic ketoacidosis (DKA) is a dangerous complication faced by people with diabetes…

Sick Day Rules for Diabetes

Managing diabetes on sick days requires special attention, as illness can significantly…

Inflammation: Definition, Causes, Symptoms, Treatment

Inflammation is a term often associated with long-term conditions like diabetes. Learn…