Allergies and allergy testing

Allergies come up in gynaecology more often than you would expect – only rarely under that name. They appear as itching in the genital area that looks like thrush and is not, as asthma that gets out of hand in pregnancy, or as the question of which tablet you may take for hay fever when you are pregnant. This page sorts that out.

What happens in an allergy

The immune system classifies a substance that is harmless in itself as dangerous and forms antibodies of the IgE class against it. These settle on mast cells in the tissue. At the next contact with the same substance the allergens dock on, the mast cells burst open and release histamine and other messenger substances. What then happens – itching, swelling, redness, a runny nose, narrowing of the airways – is the effect of those messengers.

At the first contact nothing visible happens; it only serves to sensitise. That is why allergies develop against things that have been used without trouble for years – a circumstance that regularly causes confusion.

Besides this immediate type there is the delayed type, in which the reaction is carried not by antibodies but by T cells. It shows itself only after one to three days and appears as eczema. For the genital area it is precisely this type that matters most – and it is investigated with different tests from the immediate type.

Itching in the genital area: almost never thrush

This is the commonest point of contact between allergy and gynaecology. A woman has been itching for weeks, has tried three antifungal products from the pharmacy, and it is getting worse rather than better.

The reason is usually that it was never thrush. Vaginal thrush typically causes whitish, crumbly discharge and itching; contact eczema causes itching, burning, redness and dry, cracked skin – without increased discharge. And treatment with ever more creams makes it worse, because the base substances of the creams themselves become triggers.

The commonest triggers in the genital area:

• Fragrances in intimate washes, panty liners, toilet paper and wet wipes
• Preservatives in creams and lubricants, above all methylisothiazolinone
• Latex in condoms and diaphragms
• Spermicides, in particular nonoxynol-9
• Active and base substances of antifungal and steroid creams
• Textiles and detergents, especially with tight, non-breathable clothing

The first step in treatment is therefore almost always the same, and surprises many because it is the opposite of what you expect from treatment: leave things out rather than add them. No intimate wash, no panty liners in everyday life, no perfumed toilet paper, no wet wipes. Wash with clear, lukewarm water. Cotton underwear, no liner, nothing at night.

The genital area needs no care products. The vagina cleans itself through its own flora, and the environment is acidic – which is why soap does more harm there than good. This advice contradicts a well-advertised shelf in every chemist, and it is still correct.

Douching is the most pronounced case of this. It flushes out the protective lactobacilli and thereby demonstrably increases the frequency of bacterial vaginosis and ascending infections. Anyone douching because of an unpleasant smell is therefore treating precisely the cause of the smell – and reinforcing it. A changed smell needs examining, not washing away.

If the itching persists, it needs investigating. Besides contact eczema and thrush, lichen sclerosus, bacterial vaginosis, oestrogen deficiency after the menopause and – rarely but importantly – precursors of skin changes come into question. Itching that lasts longer than three weeks should be looked at rather than treated further.

What is connected with contraception

Two connections between allergy and contraception come up regularly, and both can be answered more clearly than first impressions suggest.

Condom intolerance. If burning and redness occur after intercourse, the trigger is more often the lubricant or a spermicide than the latex itself. A simple trial clarifies this: latex-free condoms without additives, together with a water-based lubricant free of fragrance and preservatives. If that changes nothing, a patch test is worthwhile.

“A coil because of copper allergy.” A genuine copper allergy is extremely rare. The symptoms attributed to it almost always go back to the copper coil itself – heavier and more painful bleeding is its known accompaniment and not an allergic reaction. Women who fear a copper allergy often choose the gold coil; its gold core is said to reduce corrosion. No proven advantage in effectiveness or tolerability follows from that, but it remains an understandable choice. The differences are set out in the coil comparison.

What does genuinely exist: nickel allergy, which is common in women and concerns skin contact, not the uterus. Coils contain no nickel in any relevant form.

Which tests there are

Skin prick test

The standard test for the immediate type. Drops of allergen solutions are placed on the inner forearm and the skin beneath is lightly pricked with a fine lancet. After 15 to 20 minutes it becomes apparent where a weal forms. What is typically tested is pollen, house dust mites, animal hair, moulds and common foods.

Important: antihistamines have to be stopped a few days beforehand, otherwise the test comes out falsely negative. Steroid creams at the test site as well. A positive and a negative control are always tested alongside – histamine and pure solution – because only from those can it be seen whether the skin is reacting at all that day.

Blood test for specific IgE

Antibodies against individual allergens are measured from a blood sample. The advantage: antihistamines do not interfere, and the skin does not have to be involved. The disadvantage: it costs more and is no more sensitive than the prick test.

For pregnancy this is the preferred route – not because a prick test would do harm, but because it removes the theoretical risk of a general reaction entirely.

Patch test

The test for the delayed type and therefore for contact allergies. Patches with test substances are stuck to the back and stay there for 48 hours. They are read at 48 and 72 hours, often once more after a week. During that time the back must not get wet – so showering is restricted.

This is the test that helps with persistent symptoms in the genital area. It is carried out by dermatology practices and clinics; this practice establishes that it is needed and refers you.

What a test says – and what it does not

A positive test means that sensitisation exists. It does not necessarily mean that symptoms follow from it. A considerable proportion of the population has positive test results with no symptoms at all.

So: an allergy test without symptoms is worthless, and a test result with no connection to the symptoms is misleading. What counts is the correspondence: do the symptoms occur when the contact occurs?

For the same reason, broad screening tests without a specific question make no sense. They produce findings that suggest avoidance where it is not needed – particularly with foods, where unnecessary restrictions in pregnancy can do harm.

Expressly not recommended are the commercially available tests for IgG antibodies against foods. IgG merely shows that you have eaten a food, not that you cannot tolerate it. The specialist societies advise against them unanimously.

Allergies in pregnancy

The course cannot be predicted: about a third of women feel better, a third the same and a third worse. Responsible for this are the changes in the immune system, which in pregnancy is set to tolerate the baby.

With medication a clear order applies. Locally acting preparations first: nasal sprays and eye drops with cromoglicate or antihistamines, saline nasal rinses. They barely reach the circulation.

If that is not enough, antihistamine tablets come into question. Best studied are loratadine and cetirizine; for both there are data from many thousands of pregnancies with no indication of harm. Older, sedating antihistamines are used less often today.

Steroid nasal spray is also possible and is preferred with marked symptoms, because it is more effective than antihistamines and is barely absorbed when used locally.

Do not take anything from the pharmacy without discussing it – not because everything is dangerous, but because a single sentence settles the choice and saves a great deal of uncertainty.

Asthma in pregnancy

This section is the most important on the whole page, because it runs counter to a widespread error.

Poorly controlled asthma endangers the baby considerably more than any asthma medication. An asthma attack means a lack of oxygen – for the mother and thereby immediately for the baby. Poorly controlled asthma raises the risk of pre-eclampsia, growth restriction, premature birth and low birth weight.

Even so, many women stop their medication as soon as they learn they are pregnant – out of worry that it might do harm. It is the commonest avoidable cause of deterioration.

The inhaled preparations – inhaled steroids, short- and long-acting bronchodilators – are well studied in pregnancy and are continued. The dose reaching the circulation is orders of magnitude smaller than with tablets. If you are considering a change, discuss it – do not stop anything on your own.

What can really be behind the itching

Since contact eczema is described at length above, here for completeness are the other causes – each with the feature by which it can be recognised.

Vaginal thrush. Whitish, crumbly discharge, itching, redness. It occurs more often after antibiotics, with diabetes and in pregnancy. Treatment is local; recurrent thrush needs investigating rather than being self-treated again and again.

Bacterial vaginosis. Thin, greyish discharge with a fishy smell, often without itching. It is not an infection from outside but a shift in your own flora – and a reason why intimate washes do harm: they disturb exactly the environment the protective lactobacilli need. In pregnancy it needs treating, because it raises the risk of premature birth.

Oestrogen deficiency. After the menopause the lining becomes thinner, drier and more sensitive. That shows itself as burning, dryness and pain during intercourse, often with itching. It does not improve by itself but increases – and responds very well to local treatment that barely reaches the bloodstream. The menopause score assesses this group of symptoms separately, because it goes unmentioned more often than any other.

Lichen sclerosus. A chronic inflammatory skin condition with whitish, hardened areas, tormenting itch and, over time, scarring. It is frequently taken for thrush for years. Treatment is with a steroid ointment to a fixed schedule; untreated it can lead to scarring and a slightly raised cancer risk. Making this diagnosis is one of the reasons persistent itching needs looking at rather than treating further.

Telling these apart as a rule needs nothing elaborate: looking, a wet mount under the microscope and where necessary a swab. That is done in one appointment.

Desensitisation, latex and anaphylaxis

Desensitisation – the gradual accustoming to an allergen – is not newly started in pregnancy, because general allergic reactions can occur with it. Ongoing, well-tolerated treatment is as a rule continued at the maintenance dose. If you are planning one, start it before a pregnancy or afterwards.

A latex allergy has immediate consequences in gynaecology: condoms, diaphragms and some examination gloves contain latex. There are latex-free condoms of polyurethane or polyisoprene, which are equally reliable, and latex-free gloves. Say so before the examination – then things are prepared accordingly. With a marked latex allergy it is also sensible to note it with the hospital for the birth.

For women with a known severe allergic reaction in their history: the emergency kit – adrenaline auto-injector, antihistamine, steroid – stays with you in pregnancy too and is used if needed. Adrenaline is life-saving in anaphylactic shock, and shock in the mother is more dangerous for the baby than the medicine.

Allergies in the child – what can be done to prevent them

Almost all parents with an allergy of their own ask this, and the recommendations have changed fundamentally over the past twenty years – in the opposite direction.

It used to be: avoid. Pregnant and breastfeeding women should leave out strongly allergenic foods, and the introduction of solids should be delayed. That recommendation is professionally obsolete and was even harmful – early, regular contact protects rather than sensitises.

Today it is: in pregnancy and while breastfeeding, nothing should be left out preventively. A balanced diet with fish, nuts and dairy products is expressly recommended, unless an allergy of your own speaks against it. Solids are introduced from the fifth to seventh month, including the strongly allergenic foods; holding back brings no advantage.

What genuinely protects: breastfeeding for four to six months where possible. And smoke-free air – in pregnancy and afterwards, because passive smoking is the best-established avoidable risk factor for asthma in childhood.

What does not protect: acquiring a hypoallergenic pet, banishing the existing one, or cleaning particularly thoroughly. The relationship between pets and allergies is more complicated than the idea of “less contact, less allergy” – in some studies early contact was even favourable.

Where to go from here

With persistent itching or burning in the genital area the first step is an examination with a wet mount and, if needed, swabs – so that it becomes clear whether any organism is involved at all. Make an appointment. For allergy testing in the narrower sense, referral to an allergy or dermatology service follows; whether that is needed can be settled here.