Hi,
  Your question provides a nice coincidence, since some out-of-band
e-mail requested that someone with lactose instead of milk protein
allergy start some discussion on the group.

  Quick answer:

   Lactase enzyme (Lactaid/Dairy Ease/K-Mart Dairy-Relief Caplets) is
effective if you have lactose intolerance.  If the intolerance is mild,
then a pill or two will let you drink milk, eat ice cream, and eat like
a dairy farmer thinks you should.  If the intolerance is severe, then
the pills will let you handle milk-dipped chicken, cakes made with milk,
chocolate, etc.

  Long answer (My tale of woe and recovery):

  About the time I hit 30 I pretty totally lost the ability to digest
lactose.  Up until then I'd been drinking about a quart and a half of
milk a day and cheese (well, cheeseburgers and pizza) was a staple in my
diet.

  For about 3 years I had almost continuous stomach pains that
occaissionally got severe enough to cause me to pass out.  Visits to the
doctors got diagnoses like "Stress" and "Irritable Bowel Syndrome" and a
perscription for bentyl (a smooth muscle relaxant).

  After I fell over at work and got a quick ride to hospital, I got a
pretty complete upper & lower GI, and some pretty serious indignities
done upon myself.  The verdict was that nothing was wrong, but I was
obviously in pain.  The doctor seemed to be of the opinion that I was
gay, and didn't want to admit to behaviors that were injuring my colon.

  After about 3 years of pretty unhappy times, I was saved by NPR.
Hallelujia! Well, actually what happened was that I had the clock radio
on to wake me up, and caught the tale end of a report that finished off
with a list of symptoms that I recognized: "bloated feeling, stomach
pains, lots of gas".  The report turned out to be the announcement that
lactase was now available in pill form, instead of just droplets.

  So, I spent a few days not having milkshakes, cheeseburgers, milk on
my cereal, or any of that.  And I stopped hurting so much.

  I got an appointment with a doctor friend of mine, and gave him the
rundown of the tests previously performed on me, the results of my
little experiment, and my diagnosis that I was lactose intolerant.  He
agreed with my analysis, wished more of his patients could provide the
results of their testing, and explained where and how to get Lactaid.

  For a while I religiously read labels and tracked what I was eating,
but as time has gone by I've gotten used to what brands and foods I can
handle, and which I should skip and now I mostly get caught when someone
changes a recipe.

  One of the points that can make a lactose intolerance diagnosis
difficult is that the symptoms can be either constipation and straining,
or diarrhea and sudden surprises.  The common symptom is the diarrhea.

  The first few years that I was lactose intolerant, my symptom was the
constipation.  Now it seems to vary depending on how big a dosage of
milk I get.

  For me the intolerance is severe enough that I avoid all foods that
list milk and take a lactase pill with every meal to catch the bits of
milk that might be in the breading or sause.  The lactase pill gets me
through foods that have just a little milk, though I need a couple pills
to handle things like the breaded french fries (that I assume are milk
dipped, or have lactose in the breading for that nice brown color).
Friends of mine can handle pizza or ice cream with a few pills.
Experiments have lead me to believe that I can't do that.

  I've found little performance difference between the various brands of
lactase.  I used Lactaid pretty exclusively from '88 until '93 or '94,
and then started experimenting with other brands.  Dairy Ease is nice if
you have a purse or something, but the pills are too large to carry a
lot of them in the little pill box that I keep in my pocket.  Around
here, the K-Mart brand caplets are the cheapest, and don't taste bad.
One of the other store-brands works OK, but tastes terrible.