My wife had milk of magnesia. Will it treat constipation?

Question

Hi doctor,

My 78-year-old wife, who is otherwise healthy and takes Irbesartan and Nifedipine for HBP, has had constipation for several weeks. She had some milk of magnesia a couple of days earlier that week.

She passed a great deal of the next few mornings. She has had a pretty sore stomach for the last four days, but heating pads have helped a little. She has also been very tired and has not had much of an appetite.

My wife is about 5'2" tall and weighs around 128 pounds.

Let me know.

Thanks.

Answer 1

Hi,

Welcome to icliniq.com.

I guess I am really worried about your worries.

Sorry, your wife is so sick. A 78-year-old who develops constipation for several weeks, then abdominal soreness, significant fatigue, poor appetite, and an “incredible amount” of urination after taking milk of magnesia should seek prompt medical attention, especially given her age and use of blood pressure medicines.

A couple of important notes:

What the milk of magnesia may have done is that milk of magnesia (magnesium hydroxide) works by drawing water into the bowel to soften the stool. Common side effects are abdominal cramping or pain and diarrhea.

The reasons for the large amount of urination the next morning may be:

The laxative means more fluid is taken.
The body moves fluids after a bowel movement.
Possible dehydration that can sometimes make a person feel weak and pass concentrated urine.
Less commonly, another problem such as high blood sugar, a urinary infection, or kidney problems.

I am more concerned that her symptoms started prior to the laxative (upset stomach after eating), which makes me think this may not be just a medication side effect.

I am worried about these symptoms: 78 with four days of constant abdominal pain, very low appetite, a lot of tiredness, and weeks of constipation.

They can occur with things such as:

Fecal impaction or partial obstruction of the bowel.
Severe constipation with irritation of the bowel.
Gastritis or an ulcer.
Gallbladder or pancreas problems.
Electrolyte imbalance or dehydration
Kidney problems or infection are much less common.

I would recommend a same-day evaluation by a doctor, urgent care, or emergency department, particularly if:

She has not had a good BM.
The belly looks big.
She feels sick.
She is passing very little gas.
She looks weak, confused, or excessively sleepy.
The pain is getting worse.

If I were her age, I would not wait any more days.

She might have to undergo some investigations, such as:

Abdominal exam, maybe an X-ray or CT (computed tomography).
Blood tests for kidney function, electrolytes, and magnesium level.
Urinalysis. Evaluation for fecal impaction or obstruction.

I think you should do the following until she is seen by a doctor:

Offer small, frequent sips of water or oral rehydration fluids.
Do not give any more laxatives until she is seen by a doctor, especially if she has continued abdominal pain.
Feed light foods only if tolerated.
Continue her usual medications.

If she has vomiting, fever, severe bloating, confusion, inability to pass stool or gas, or worsening pain, please come to the ER (emergency room) immediately.

This could be something simple like irritation from severe constipation, but at her age I would take the abdominal pain and weakness very seriously.

I hope this helps.

Thanks a lot.

Answer 2

Hi,

Welcome back to icliniq.com.

I get what you are saying.

“That makes a lot of sense.” That update paints a much clearer picture. The most likely diagnosis is severe constipation with fecal loading relieved by milk of magnesia, then bowel irritation (post-laxative cramping).

The following is the reason why this fits very well:

Weeks of constipation, stool packed in the colon.
Took milk of magnesia. A very powerful osmotic laxative.
Then a large amount of stool was passed, probably clearing a backlog.

Experiencing the following now: Heavy bowel evacuation is common to cause abdominal soreness. Fatigue and low appetite may occur after dehydration and bowel strain.

This is quite the usual irritation of the bowels after constipation. What probably happened physiologically:

Stool built up, and the colon enlarged.
A laxative helps to get water into the bowel. This makes the bowel move strongly.

In a major evacuation, the bowel becomes temporarily inflamed and tender. Which means:

Crampy ache.
Pain (like a muscle pulled inside the abdomen).
Loss of appetite.
Fatigue.

However, a word of caution (given her age): Even if this explanation fits, we need to be cautious at 78. A few things I still want to rule out:

Residual fecal impaction (incomplete evacuation).
Electrolyte imbalance (especially laxative use).
Partial intestinal obstruction.
Diverticulitis (common in older, constipated adults).

This is likely benign if:

The pain is slowly improving.
She is now passing gas and stool normally.
No vomit.
Not febrile.
The abdomen is not distended.
Then this is probably just post-laxative bowel irritation. If she needs urgent attention:
Pain continues or gets worse after 3 to 4 days.
The belly is distended or tender.
Throw up.
No BM or gas again.
Temperature.
Very faint or confused.

Here is what you can do now:

Fluids (important after laxatives). Encouragement.
Soft diet (light foods, porridge, soup)
Skip the stronger laxatives for now.

Gentle remedies if necessary:

Fiber, dietary.
Stool softeners (with doctor's guidance).

The diagnosis is now most consistent with severe constipation relieved by a laxative followed by temporary bowel irritation or cramping.

That said, if she is still pretty sore after four days, I would still recommend a doctor visit, just to be safe given her age. If you like, I can help you put together a safe, long-term constipation plan for her so this does not happen again

Hopefully that helps.

Thanks.