do you have animals? any smells in any area fo the house? funny thing is that people who live in a home rarely smell the ongoing smells.

how long have you lived there?

have you had anyone check the house for mold?

How about a certified Home Inspector?

Do you know what they are allergic to? Could be mold, certain plants, animals, dust, fumes from heating oil, gas, sewer, paints, perfume, soap, laundry detergent, scented candles, air fresheners. The list is huge. Unless you know what they are allergic to where do you begin?

a certified home inspector won't tell you squat unless they are also certified to perform (and actually do) allergen and mold tests.

i tend to lean towards somethign in the house such as the dust/pet dander/type of air freshener/etc. my wife used to use air fresheners all the time. i was always getting headaches/nausea. she ran out once and forgot to pick some up at the store and what do you know, my illness went away the 2nd day! she finally got some and soon as she sprayed it came back. only seems to happen with certain aeresol sprays, some will affect me but most won't.

There are already many good replies already. As joed wrote, there is a huge list of things that can cause reactions. And, as you've discovered, different people can react in different ways to the same thing.

We had a similar problem in our home that turned out to be highly elevated mold spore levels. This was the result of a plumbing related flood.

Below is a link to an excellent book that covers all sorts of things that can impact indoor air quality. The title of the book sounds alarmist but the book itself is not. It's written by an industrial hygienist that has inspected hundreds of homes. This book won't tell you what the problem is in your home but it will give you an idea of things to consider. And sometimes the solutions are easy an inexpensive.

You might be able to find a copy at your local library. That's where I first found it after reading some positive reviews on Amazon.com. Later I ended up buying a copy from half.com.

Good luck!

Bob

Here is a link that might be useful: My House is Killing Me: The Home Guide for Families With Allergies and Asthma

Fabric softner, perfume, news plants, christmas tree sprayed with fake pine scent, febreeze, dead or live animals stuck in ventillation system.

Another idea is to check and change the furnace filters...

Just a thought.....This also sounds much like people who live in lower elevations visiting someone at a higher elevations. You say it lasts only for a day or two which means they are becoming aclimated.

When I was first married and had small children , we bought a brand new
modular home and my baby had breathing and asthma problems as soon as
he came home from the hospital . This went on for a year and a half . After
seeing specialists , getting tests for cystic fibrosis , allergies , etc . my pediatrician askedus to check with the home manufacturer about formaldahyde .
When we checked - we were shocked that there was formaldahyde in almost
everything . The walls , insulation , carpets and cabinets . She suggested we move . So we immediately bought another house and moved . His health
improved immediately .

Do you spray all over before they come with "air freshener" or do you spray furniture cleaner?
There is a church in town who's janitor or someone puts some sort of odor eliminators in every bathroom and hall way to eliminate the "stale smell". My eyes water, my throat catches and I wheeze. I won't go to a funeral there....and I don;'t know what to do if I am ever invited to a wedding there!
Try new furnace filters, vacuum well, switch to All Free and clear for detergent on your linens and go over everything with a damp cloth before their next visit.....something's got to work.
Linda c

Any smokers in the house?

Wonder what happened to the original poster. :-[

Could be outside the house. GF moved into old house & her DH got sick almost immediately. Ear, nose & throat dr was irrigating his sinus often, using antibodics on him, his eyes were black around them like he had been punched by someone. Turned out the side yard had hedge of honeysuckle, front yard had pepper trees. After they moved his illness went away. Japanese Pivot(sp) a hedge with cream flowers & shiny leaves used all over CA. Is 1 of things drs do not check for when they are doing allergy tests. It requires special test even though it is major cause of allergies. Smoke can be very serious allergy, smoke can be from smoking, candles in a room, fire in firepit, BarBQ, forest fire. Even pipe or cigar smoke. Extra cold house, I had GF that had GS that slept under the covers, he said he got sick in her house otherwise. So hope she comes back to forum & finds out the problem & tells us what it was. Often takes awhile to figure out what the source is.