How does vitamin D-3 kill mice and rats?

Q. I had a little mouse problem, so I went to buy some mouse poison.

I’d always heard D-Con used a potent blood thinner called warfarin. I was surprised to find that D-Con now contains cholecalciferol, vitamin D-3, instead. How does that work?

A. Many rodenticides (mouse and rat poisons) used to contain anticoagulants like warfarin. This drug works by causing internal bleeding. Warfarin is still used in human medicine in carefully monitored doses to prevent blood clots.

While some rodenticides may still contain warfarin, there are now other options. Bromethalin is a neurotoxin that leads to paralysis. Cholecalciferol (vitamin D-3) has been used for decades. At high doses, this hormone causes blood calcium to rise to toxic levels. This, in turn, leads to kidney damage, bleeding and heart problems. Mouse poison is toxic to pets and must be kept well out of their reach.

As with all poisons, the dose is critical. That is why the tolerable upper limit is set at 4,000 IUs for adult humans.

Q. I have osteoarthritis of the knees and back. Some days I can barely get out of bed. My primary-care doctor advised me to take hydrocodone every eight hours as needed.

Taking opioids regularly worries me, so I haven’t taken this medicine recently. What else can I do to deal with the pain and stiffness?

A. You and millions of other arthritis sufferers are caught between the proverbial rock and hard place. Oral medicines like opioids or NSAIDs (celecoxib, diclofenac, ibuprofen, naproxen, etc.) have potentially serious side effects.

In a study published in JAMA (March 6, 2018), opioids proved no better than medications like acetaminophen, NSAIDs and antidepressants (amitriptyline, etc.) or liniments containing capsaicin or lidocaine.

Topical NSAIDs such as diclofenac gel or patch (Flector patch, Voltaren Gel, etc.) may have fewer systemic side effects than oral medicines (British Journal of Sports Medicine, May 2018).

Q. I have tried everything for nasal congestion. Although some remedies work for a while, nothing has worked consistently over the years better than nose spray. The problem: It is addictive.

My congestion is always at night, so I either use the spray or can’t sleep. I have tried oral decongestants. They clear up my nasal passages, but the ingredients keep me awake. I also have tried nasal strips with little success.

A. You are caught in a classic double bind. Many people find that oral decongestants keep them awake. If an antihistamine also has a “D” in the name, it probably contains a decongestant.

Perhaps an allergist could identify what is causing your congestion and recommend nonstimulant options. Avoiding the triggers that are causing the congestion would be the best solution.

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