I see that this thread is not recently new. But here is some information anyway for the original poster, or for other readers who come here:

Basically Sulfasalazine is a sulfonamide. If you are allergic, that would be a contraindication for its use.

The two major factors about are:
1) may cause photosensitive reactions when you are exposed to UV light (outside or tanning booths). I'd caution against tanning booths EVER with this drug...I've seen horrible reactions to UV that lasted for weeks. Tanning booths do very high UV in a short period of time (usually 20 minutes to a 1/2 hr), and this really may activate a reaction that would be minimal in the outside.

2) This drug depletes folic acid, so ask the doctor if he will give you folate along with it. Most doctors do give the folic acid with it. Sulfasalzine blocks absorption of folate from the GI tract.

This drug can be messy to store, and leave residue of powder behind. For this reason, handle carefully to prevent contaminating your home or office. Some people can inhale the residue that gets into the air and have allergic responses, if they are allergic. This depends on the manufacturer of the product you finally receive, and you will see then if residue is present. Also for this reason, don't mix this tablet with others in drug dispensing devices, or in other bottles. Throw away empty containers and don't reuse.

An allergy may develop over time with exposure to it, so be watchful for a fine red rash that often appears over the chest and back and arms first. At any sign of rash, discontinue and consult your doctor. If you continue with it during an allergy reaction, a serious condition may develop, called Stevens-Johnson syndrome. However, many people use sulfasalazine with no allergic response.

Here is a general overview for this drug:
http://www.medicinenet.com/sulfasalazine/article.htm