Following two paragraphs lifted shamelessly from Microsoft Bookshelf:

The name poison oak is often applied to the shrub-like forms of poison ivy and to at least two similar plants that are usually considered separate species of the cashew family, Anacardiaceae.

The poison oak of the southeastern United States, Rhus quercifolia, has its leaves divided into three leaflets; the leaflets are densely haired and generally have three to seven distinct lobes. The white, berry-like fruits are also somewhat hairy. The poison oak of the U.S. Pacific coast, R. diversiloba, is a shrubby or sometimes climbing plant that grows to 2.4 m (8 ft) high; its three-leaflet leaves are toothed or lobed and are hairless. Both species contain poisonous substances that are believed to be identical or closely related to that found in poison ivy.

Poison Oak is usually not found above 4000 feet elevation (1219 metres).

You can get Poison Oak by touching the plant, its leaves, roots, whatever. If an animal, such as your dog, gets in Poison Oak you can get it from petting the dog (the dog won't get the rash though). You can get it from your clothing that touches Poison Oak.

Whatever you do, don't burn it!

So the answer is no, once you get the rash, you can't spread it around by scratching. The oil that seeps from your wounded body isn't urushiol, its secreted by your body.

The reason most people think it will spread is because of secondary infection. You touch a poison oak plant, the oil is on your hands. You rub your face, it gets there. The oil is spread. Now after a while, there isn't as much oil to spread around, so some parts get hit more heavily. What this means is, the rash appears soon is some spots, and takes a couple of days in other spots. This gives the illusion that you've spread the rash by scratching or whatever.

Just make sure you aren't getting brand-new infection from your clothing. Whenever I go hiking, as soon as I get home I put all my clothes, shoes, everything in a bag, and wash it all. Only through extreme paranoia can you avoid poison oak. The alternative is to never go anywhere fun.

Remedies

Q:I have Poison Oak! What do I do?!

A:Well, you can suffer. That's about all you can do. Well, there are a few other things. If you don't do anything, you'll be totally miserable for about 2 weeks, maybe less, depending on how bad it is.

Q: Does Calamine lotion help?

A:Not really. It may help a bit for minor affliction, but is basically worthless. Hydrocortisone is pretty useless as well. Some poeople can find relief from these products. If you can, good luck. But if it is bad, what you want is Prednisone. See the next entry.

Q:Should I go to the doctor?

A:If it is very bad, go to the doctor. Prednisone, a type of steroid, is very effective but may increase the likelihood of infection with prolonged use, so they will only prescribe it for about a week's worth of medication in descending dosage. (Of course, if you have Poison Oak, I doubt you'll care very much about an itty bitty infection!)
Atarax, or hydroxyzine if you buy generic, is supposed to make it itch less. It will make you very drowsy though. If your doctor does not know about these two medications get another doctor.

Q:Does hot water help?

A:There are different schools of thought on this subject. My opinion: Hot water makes it feel better only so long as you are running hot water over it. As soon as you stop it feels a whole lot worse. Other people find that hot water can help.

Submission: Another way (Dr. Bob Sheppard of Carrollton, AL) has found relief (for poison ivy) is to hold the affected area under running, hot water. "For temporary relief, go to the faucet and turn the hot water on to the point where it is almost uncomfortable. Put the infected area in the running water," he said. "What you will notice is that the area will itch intensely," he added. "Continue to do this for a minute to a minute and a half, (and) finally, you'll begin to notice that the rash area is not itching anymore. And for four to five hours, you won't itch."

Submission: I really enjoyed your information that you provided although I do dissagree with one of your no nos...which is the hot water trick that actually for some gives tremendous relief...what it does is allows all the histimine that is building up in your system to become released. Histimine is what causes the itch..itch...itch.It is only a temporary relief but it does last up to 8 hours or untill the histimine builds back up. Also you should tell everyone the shower should be a very COLD one at the time of infection to close the pores and wash off the poison oak.

Other Remedies

Submission: P.S. Other medications that are used instead of prednisone are a Medrol Dosepak (medroxyprednisolone) or Decadron (dexamethasone). They are also corticosteriods. Instead of pills the Medrol or Decadron can be given as a shot. This is the route I prefer as I don't have to bother taking pills. I don't know much about poison oak, but I do know that Domboro soaks work good on poison ivy to dry it up. If poison oak is worse than these would probably work well on it as well.
NOTE: This is from the wonderful pharmacist who corrected my spelling of prednisone (I was mixing up my 's' and 'z'). Thanks!

Submission: I saw your web page and what I've been using as a treatment seems to be just about the best around. They're products by Tec Laboratories in Albany Oregon: tecnu and CalaGel.
Note: I haven't had a chance to check out Tecnu's products yet, but when I do, maybe I'll post a review or something.

Submission: The mugwort plant is said to have a soothing effect on Poison Oak and may possibly prevent an outbreak if applied quickly.often. Bruise the Mugword leaves and rub on the exposed area. Poison Oak and Mugwort often grow near each other.

Submission: My docter gave me the predisone, which really helped and also suggested an over the counter gel. Rhuli gel, which helped relieve the itching.

Submission: Aloe vera from the plant helps dry it locally. Problem with poison oak is that is gets into your blood and comes out in other areas of the body... Hot water aggrevates, bright sunlight irritates and sweating makes poison oak it feel worst. Mud packs help to draw the poison out of the skin. Rinse with cold water.

Submission: I have just begun to produce homemade soap which I am making from jewelweed, nettle, comfrey leaves, plantain, burdock, and aloe vera extracts and tallow, lard , olive oil, and lye. It seems to be working as I go into the woods to gather jewelweed and nettle and have not got any poison ivy yet. I immediately bathe with my soap following my expeditions. Maybe I have found the cure!

Submission: It helps if you pee on it.