Why have I developed my allergy now, when I have been using the same product for years?
People are not born allergic to substances, but they can develop contact allergies at any time during their life. To become allergic to something, you must have been exposed to it before. Whilst it is possible that someone can develop allergic contact dermatitis to something after only using it once, there is often a long history of exposure to or use of a substance before a person becomes allergic to it. The exact reasons that some people develop allergy, whilst others do not are poorly understood. The timing of allergy developing is also often unclear.
How long will I be allergic to this substance?
Unfortunately, the type of allergy that causes allergic contact dermatitis lasts for life. You will therefore have to continue to avoid exposure to the problem substance for the rest of your life. Your body has learnt to react to this substance and each time that you are exposed to it, it will produce an allergic reaction (skin rash).
Can it be treated?
The rash that develops can be treated, but there is no cure or treatment that will stop you being allergic to a substance. The best treatment is to avoid exposure to the substance in the future. By contrast, some allergens that cause immediate reactions, such as grass, mould and trees causing hay fever and asthma, can be treated with desensitisation. This is performed by allergists and is not available in our clinic.
Will I develop more allergies?
There is always the chance that you will develop contact allergy to other substances in the future. This might happen to substances that you have been tested to before, and were not allergic to at that time. This means that a negative patch test now does not mean that you will not become allergic to a substance in the future.
Apart from patch testing, is there any other way to diagnose allergic contact dermatitis?
Unfortunately there is not. Patch testing has been used for over 100 years to investigate the causes of allergic contact dermatitis. There have been advances with the technology that is used, but the basic process has remained the same. Other types of allergy such as contact urticaria can be investigated in different ways, for example by skin prick testing and special blood tests. These are often performed alongside patch testing if the patients’ story suggests that there is more then one type of allergy present. Prick testing is often used to diagnose food allergies or allergies to grass and pollens.
Is this all I am allergic to?
We can only diagnose contact allergy by testing you to a substance. Over 4,000 substances have been reported to cause allergic contact dermatitis, so it is not possible to test you to all of these!
We therefore interview each patient to help decide what the most likely problem substances are, and test these. If you or we do not suspect a particular substance, then we might not test it, and this allergy would remain unknown.
How long will it take my skin to get better?
This is a difficult question. If the particular substance can be avoided, then the rash should settle within a few weeks. This will take longer if there is continued exposure, or if the initial rash was very severe or had been present for a long time.
It is important to use the treatments for the rash that your doctor or dermatologist has suggested, until the rash has resolved. The skin will remain quite easily irritated for some time after it appears to be better, so good skin care is essential.
Sometimes additional treatments may be required. These include ultra-violet light treatment or Grenz ray treatment. Patients are normally referred back to their referring doctors for such treatments. In addition, sometimes oral (tablet) medications may be necessary for a while, to treat some more severe cases of dermatitis.
What if my skin doesn’t get better?
There may be many reasons why your skin does not get better:
- There might be continuing exposure which you are not aware of to a substance that you are allergic to.
- If the initial rash was very severe, it can sometimes take many weeks to resolve.
- You may not be receiving the correct treatment – discuss this with your doctor or dermatologist
- It is possible that you are allergic to other substances that were not tested for during patch testing. You may still be exposed to these, and these may be stopping your skin from returning to normal.
- Because your skin can be easily irritated, even frequent hand washing and ‘wet work’ may be a problem.
All of my patch tests are negative, what does this mean?
There are two main types of contact dermatitis: allergic contact dermatitis and irritant contact dermatitis. Allergic contact dermatitis is diagnosed by patch testing. Irritant contact dermatitis is the most common type of dermatitis but there is no specific test for it. Instead it is diagnosed based on your history of exposure to different substances, and negative patch tests. There may also be other skin conditions which could be the cause of the problem and the dermatologist will discuss these with you.