What Makes This Happen???

One possible reason is Pepto-Bismol (or other drugs that have bismuth as an ingredient e.g. Kaopectate). Other reasons are overgrowth of bacteria or yeast on the tongue (http://pediatrics.about.com/od/weeklyquestion/a/1106_blk_... )

I agree aobut the pepto as others said...it always does this to me...sometimes a day later after I forgot I took the stuff. I am just used to it now!

OK..after I stopped laughing (not because your SIL has a black tounge, but because of your insinuation based on her boyfriend's occupation) I googled black tounge and here is what I found as far as causes (from mayoclinic.com)

■Changes in the normal bacteria or yeast content of the mouth following antibiotic use

■Poor oral hygiene

■Breathing through your mouth

■Medications containing bismuth, such as Pepto-Bismol

■Regular use of mouthwashes containing oxidizing agents, such as peroxide, or astringent agents, such as witch hazel or menthol

■Heavy tobacco use

I would go ahead and send her to the Dr.

did she take pepto bismol?

Pepto Bismal causes this. If you take pepto the night before, when you wake up your tongue is black. It brushes off.

If it's not a pepto thing, I'd make an appt at the doctors.

I get a black tongue sometimes after I eat a peptobiz tab. Ask her if she has a black tongue after eating one.

I agree it could be Pepto Bismol if she has been taking that, or some other medicine she's taking.

I took Pepto before bed once w/out drinking anything afterward. Woke up w/ a dark colored tongue! haha

This happened to me once about 10 yrs ago. I think it was food poisoning. I rushed over to the dr by then the dark black and lighten up a bit. By the next morning my tongue was looking normal. I was scared.

I had something similar when I had an allergic reaction to penicillin. If she gets any other allergy symptoms, see a doc. (things like hives, itching, splotches, difficulty breathing)

I've heard where they call this "hairy tongue"..check that out on the mayo website.

Look up "black hairy tongue" on Wikipedia.

It can be caused by abx, but it is very often a reflection of severe fungal overgrowth. I have gotten one many times after being on abx and I have ongoing issues with fungal overgrowth. Probiotics can help alot with this, as can a low carb diet. Fungal infections can be transferred from one person to another, so if the bf has fungal overgrowth, then she could have gotten it from him. Many people have fungal overgrowth due to overconsumption of carbs - ie., Standard American Diet (SAD).

I think she got it from the truck driver :)

Some antibiotics cause hairy black tongue. Just curious.....what does having a truck driver boyfriend have to do with your SIL's condition?

Very poor nutrition will cause a black tounge. Also, the bismoth in peptobismal with cause a dark tounge for a couple of hours.

Is she taking antibiotics???? This can sometimes cause the tongue to turn black, she needs to check with her doctor.....super infections/ABX might be the cause!!!!