Itchy Lace Dress

You might be able to put in a thin piece of fabric u
On the underside of the lace where the sleeves are. Or tuck a scarf under...

Is there any way they can alter them slightly and add a band of silk where they encircle your arm? That might help.

I had the same problem. My seamstress said she’ll as silk or satin underneath so that the fabric isn’t directly touching my arm

These days, most gown fabrics on the inexpensive side, have a sizing or fine coating ( like clothes get when you put a fabric softener in the rinse water. Some have ammonia or formaldehyde as part of their makeup, others may even have a pesticide so in huge shipments with things in containers, no pests damage the goods. USA, Canada, much of Europe have outlawed a couple if major treatments for fabrics for toxicity to industry workers handling the fabrics, and wearers of the garments. But they are widely used in China, India, Bangladesh, Pakistan, and other places that now produce huge amounts of textile goods for the American market. So you likely are sensitive to one of these substances, or to the petroleum base used for synthetic lace or the satin the cap sleeves are made if. One fabric may be coated, another in the same dress nit, because the coatings are put in before fabric is cut for the dress. So if the silky lining of your skirt does not bother you, but silky lining of bodice or sleeves does, they are look alike fabrics from different sources, and one clearly has stuff you are allergic to. Your reaction is called contact dermatitis, because something is absorbed through your skin whenever in contact with the stuff, and your body is upset, reacts. This is why all sheets, towels, and clothing, come with warnings to wash before using. Unfortunately, many fancy fabrics in gowns cannot be washed in soap and water, so you cannot get rid if the sizing or fabric finishing solutions. Dry cleaning does not do it.

Ask seamstress for advice! Maybe can add some soft fabric beneath the lace fabric.

Ask the seamstress you did the alterations to add in a patch of silk underneath the sleeves! I have the same problem.

I had this issue with costumes when I danced. If you put a thin layer of vaseline on your arm it will help (the other trick to to cut a pair of hose and wear it around your arm but I'm pretty sure it would be way more noticeable in a wedding dress then a dance costume lol)

One thing you can try is to rub the lace with fabric softener sheets...this can make the lace softer and less itchy.