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When summer rolls around, many people look forward to long days out in the sunshine, in a beer garden, enjoying the great outdoors. What’s not to love about basking in the glorious warmth of a summer’s day? Well, for a lot of people, the onset of summer also signals the arrival of a much more unwelcome period of the year; hayfever season.

Allergic rhinitis is one of the most common and best-known allergies in the world with as much as 30% of the adult population of the world affected. If you don’t have it, you most definitely will known someone who has it. Other allergies such as peanut, dairy, shellfish and egg enjoy high levels of prevalence and awareness. But, for a small, unfortunate section of the population, their allergies don’t enjoy the same level of awareness, which can affect the level of research given to them. So, to do our bit, here are a few of the worlds rarest and strangest allergies that even allergy testing struggles to find.


Hayfever sufferers thought they had it bad when it came to summer? Believed to affect 3.1 people in every 100,000, solar urticaria can have significant adverse effects on your ability to lead a normal lifestyle. People suffering from solar urticaria will experience severe rashes, hives and other significant dermatological symptoms whenever their skin comes into direct contact with sunlight. For most, wearing clothes to cover up the skin will protect them from the more severe symptoms but there have been instances where even this hasn’t offered protection.

Allergy testing is not effective in this case as it is difficult to expose a sample of skin to daylight and observe a reaction. Unfortunately, the best way to diagnose is to expose the patient to a small amount of sunlight and observe the reaction on the body.

There are several different forms of treatment which range from antihistamines to limited exposure to build up tolerance.



You’ve read that right. The substance that makes up around 60% of the human body is, for some, an allergen. Aquagenic urticaria is thought to have affected around 100 people. Ever. This incredibly rare allergy makes life incredibly difficult for the sufferer. When you think of all the things you do, eat or drink that involve water, you start to get an idea of the extent of the problem this causes.

Sufferers have to severely restrict bathing to just a couple of times a week and avoid drinking water where possible, instead having to drink sugar free soft drinks to stay hydrated.

If a sufferer comes into prolonged, significant contact with water they could be exposing themselves to potentially lethal symptoms like swelling of the throat. The best current form of treatment is limiting exposure combined with antihistamines. There is currently no cure.

As opposed to traditional allergy testing such as blood or hair, it is diagnosed with limited exposure to observe any reaction.


Whilst still considered rare, this allergy is more common than you realise with one survey finding a figure as high as 8%. This particularly allergy causes severe rashes, itching and hives in the area that has come into contact with semen. In some cases, the symptoms can spread across the whole body, but typically they’re experienced locally to the contact point. In severe cases, anaphylaxis can occur.

Again, traditional allergy testing doesn’t cut the mustard here. To identify this particular allergy, your doctor will require a sample of your partners semen which they will then dilute and inject a small amount under your skin and wait for a reaction.

The best course of treatment available is to use a condom, but for those wishing to get pregnant they can go through a process called desensitisation during which you’re repeatedly exposed to small doses to build up immunity.

Allergy Testing

Whilst the above, rare allergies are undetectable by traditional allergy testing methods, the most common allergies are easily identified with a test. You can find allergy testing to suit all budgets here.