The Lactose Intolerance Clearinghouse Has Moved.

My old website can be found at I am no longer updating the site, so there will be dead links. The static information provided by me is still sound.

For quick offline reference, you can purchase Planet Lactose: The Best of the Blog as an ebook on or or or a whole lot of other places that Smashwords is suppose to distribute the book to. Almost 100,000 words on LI, allergies, milk products, milk-free products, and the genetics of intolerance, along with large helpings of the weirdness that is the Net.

I suffer the universal malady of spam and adbots, so I moderate comments here. That may mean you'll see a long lag before I remember to check the site and approve them. Despite the gap, you'll always get your say. I read every single one, and every legitimate one gets posted.

Sunday, April 26, 2009

How Long Does a Lactose Attack Last?

I hate getting questions that I can't answer, but "it depends" is all-too-often the only real comment that I can make.

This was in an email I recently received:

After reading pretty much everything on your website and a lot of others, I still haven't found the answer to this question: How long after you stop consuming lactose does it clear your system and stop causing symptoms? Are there any residual effects and/or damage to the gut?

There is very little that's more individual than a lactose attack. It varies not just by person to person, but every single time you take in more lactose than you can digest. How much lactose you eat, whether it's part of a meal or whether it's mostly liquid, how much lactase may remain in your system, and how sensitive your intestines are all play a major role.

The symptoms may be mild or severe and may last for a short time or for quite a while.

You cannot damage the gut by having lactose. If you are particularly sensitive or also have Irritable Bowel Syndrome, your intestines may keep on spasming even after the lactose is gone. At that point taking an antidiarrheal drug to stop the spasming is a good idea. Don't take one right away thinking that you're stopping the symptoms. You'd just be keeping the lactose in you longer.

Extreme cases of lactose intolerance (LI), meaning times when someone keeps having milk despite the symptoms, can lead to dehydration from the water loss. That used to happen in the days before people knew what LI was. (If you didn't know that milk caused your problem you wouldn't think to stop having it.) I haven't heard of a case of dehydration in a very long time. Knowing all about LI is far too common in the U.S. This might be a concern in some other countries where understanding of LI is just beginning to reach our levels.

LI is uncomfortable but not dangerous. The sympotms will go away when the lactose is gone (and you make sure not take in more lactose). It just seems like forever.

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mgloberman said...

Re: How long an episode lasts. I have experienced extreem discomfort for over two days. I found that taking a product like Imodium will give substantial relief within an hour!!

I also found that you can not generalize about foods. For example, I can eat a well aged (hard yellow) cheese such as Swiss, mozzarella etc. without any reaction. But a similar named cheese that is softer, creamier ,and not as yellow that has not been aged as long will cause distress!
Hope this helps someone -- mel Globerman, Lake Worth, FL.

Anonymous said...

FYI mozzarella is only aged for about 30 days and quite often causes problems for those that are LI.

Very hard aged cheeses such as parmesan, romano and cheddar contain much less lactose and are less likely to cause a problem.

Anonymous said...

I had shared a small shake and have been having nausea for the past two days. How long would it last? Or is there anything I should do? Also I've been vomiting.

Anonymous said...

I am suffering from the effects of a 4 oz. milk shake now for the third day. The first night I had diarriah thru the night and threw up twice. I also had very uncomfortable stomach cramps. I am very worried that these symptoms will last for months like my first bout with lactose intolerance. Which lasted several months. Besides staying away from lactose is there anything else I can do to feel better. I honestly thought I wouldn't have any reaction when I drank the milk shake, because I have been feeling so good. Right now, even tho I'm staying away from lactose entirely, I am still quite sick.
Thank you for any help.

Christina said...

As a severely lactose intolerant individual, the only thing I can have is aged Sheeps cheese. Cheese aged over 12 months or more is lactose free. I go for the two year reserve stuff and even then, just a little and not too often.

Unknown said...

Why do some things affect me more than others? I can occasionally drink milk with only mild cramps and gas, cheese doesn't bother me much, yogurt doesn't really bother me, but ice cream used to bother me so bad I'd have to go to the hospital. I haven't ate ice cream in a while but the last time I had it these symptoms didn't occur.why does it only happen sometimes,worse with some dairy products,and different severities?

Anonymous said...

Sucrose in particular (sugar) seems to aggravate symptoms of intestinal sensitivity for some. (Check out the "Specific Carbohydrate
Diet"for more information)

Monique said...

Do you have a milk allergy? Those symptoms are more severe... Sounds more like what you described!,