A Laxative that Works at Both Ends

  • Published
  • 3 mins read

“Dear Pharmacist,

I heard you recommend a drug called Lactulose as a laxative but you said it helped with brain fog too. How can it work at both ends?”
–J.C., Decatur, Illinois

Answer: It’s true, the prescription medication called Lactulose, is a classified as an “osmotic laxative” which means that it pulls water into the bowel, and it also affects brain function by removing ammonia, a potent neurotoxin which is more common than you think. Mira Lax is another good laxative in this drug category.

Lactulose is not naturally occurring like psyllium is, it is synthetic. Lactulose is a non-digestible sugar, which treats both constipation and hepatic encephalopathy. That last one is a complication of liver disease that causes neurological problems by increasing ammonia in the body.

Lactulose is tasty, inexpensive and carried by pharmacies. The dosage varies based upon your response, and what you’re treating (ie constipation or encephalopathy).   Start with a low dosage and gradually increase if needed. A typical dose might be one or two tablespoons by mouth every day, but again, you can go up or down from there, depending on what your doctor says is right for you. Lactulose can cause severe dehydration and depletion of electrolytes which can affect the heart so a trace mineral supplement (taken 60 minutes or more away from the Lactulose) may be needed, especially magnesium which runs the heart. Drink water during the day.

Once you take a dose of lactulose, the sugar molecules (which never get digested, so don’t worry if you have diabetes), get broken down by the bacteria that live in the lower part of your gut. Probiotics are needed to metabolize Lactulose. In fact, if you had a healthy probiotic stash, you probably wouldn’t have constipation to begin with. But anyway, the probiotics in your colon digest the lactulose and  produce compounds that cause a little more acidity in your lower bowel (you want that, it has nothing to do with acid reflux so don’t worry).  As a result, more water is retained in your bowel, and thus more water in your stools. It softens them, making them easier to pass. Lactulose is particularly helpful for people in nursing homes. It takes a few days to begin working.

Lactulose helps draw ammonia out of the body, which can become elevated in people with liver cirrhosis as well as Lyme disease patients. True story, you didn’t know? The Lyme germ (from tick bites) can raise ammonia in the brain, which then causes astrocyte swelling, and that triggers nasty neurological symptoms such as mild encephalopathy, brain fog, lightheadedness, fatigue, body pain, confusion, visual disturbances and altered sense perception. There are more specific ways to treat this, the topic of a future column.

The drug valproic acid may increase ammonia and lactulose helps.  Inborn errors of metabolism increase ammonia. Usually, the condition requires intravenous drug treatment but in mild cases, a prescription for lactulose solution is pretty common along with a protein-restricted diet.