Do painkillers have any short-term effects on liver function tests?

March 1, 2017 12:28 PM

I'm on medication that potentially affects the liver, and I'm trying to schedule a physical and get bloodwork done before my next medication followup visit. I'm also in the middle of a root canal and have been popping Tylenols off and on all week. Do I need to be concerned about that affecting the lab results?

I've been taking moderate but steady doses of Tylenol (one or two tablets at a time, 1-3 times a day) since my tooth started hurting on Saturday. All of my googling so far just discusses liver damage from long-term use of high doses of painkillers, or adverse test results without specifics.

I'm still taking the occasional Tylenol now for post-dental work aches and pains, though I could get by without if needed. I'm due in for the second endodontist visit next Tuesday and I'm trying to squeeze this physical in before my med appointment next Saturday.

Normally I wouldn't be too concerned but I started on an antidepressant a couple months ago and I've had issues with meds+liver in the past, so I'd really like to make sure the lab results are accurately reflecting the chronic antidepressant use and not the short-term surge in painkillers. Will this be a problem? If yes, how long should I wait after I stop taking the Tylenol to go in for bloodwork?

posted by Dr. Sock, WebMD to Health & Fitness (11 answers total)

Best answer: There are studies showing significant effects on liver enzymes in the first few weeks of regular acetaminophen use (albeit at higher doses than it sounds like you're taking). This is a question you should ask your doctor, not MetaFilter, especially since you've had liver issues with medication, but if it were me, I'd postpone the physical.
posted by kindall at 1:06 PM on March 1, 2017

FWIW, my dentist tells me that acetaminophen (or brand-name Tylenol if you want to pay extra for the name) is not the best OTC med for tooth pain. They recommend ibuprofen, 600mg.
posted by JimN2TAW at 1:36 PM on March 1, 2017 [4 favorites]

So this is 100% purely anecdotal but my DH has been forbidden from taking Tylenol or anything liver-reactive (vitamins, etc) by more than one MD because of his recurring high liver enzymes. I would knock those Tylenol right out of your hand.

If you can tolerate it, take ibuprofen.
posted by fiercekitten at 1:38 PM on March 1, 2017

Since Tylenol can also affect your liver, if you haven't done this already, you really need to call either your doctor or a pharmacist and make sure it's OK to take with the pain medication you're on regardless of what might happen with your liver function tests. Please, please, please do this before taking any more Tylenol. IANAD, but I know that people who combine alcohol and Tylenol can severely damage their livers, so taking it with a pain medication that affects your liver is probably not good.
posted by FencingGal at 2:09 PM on March 1, 2017 [1 favorite]

Best answer: I've taken care of hundreds of liver patients over my career as a hepatology nurse. We always recommended patients avoid acetaminophen if at all possible. You might not know this, but a significant reason for emergency liver transplantation is due to liver failure from acetaminophen, although this is usually connected to deliberate overdose in suicide attempts. There is literally no antidote to Tylenol once it has metabolized, and if not found in time it is a very effective way to commit suicide. Liver damage takes surprisingly low Tylenol doses, which is why most of the world limits the size of packages sold and sometimes even blister-packs the medication.

Your use doesn't seem too alarming, although if you are taking 6 extra strength tablets a day (3000 mg) you are skating close to the edge of too much. Most importantly DO NOT DRINK ALCOHOL WHILE USING ACETAMINOPHEN. The combination reduces the amount of Tylenol needed to cause liver damage.

I would delay your blood testing, which you want to focus on your possible antidepressant enzyme bump. Testing now will only confuse the issue you are asking about.
posted by citygirl at 2:35 PM on March 1, 2017 [4 favorites]

I am on meds that affect liver function (have monthly testing) and have been told to avoid Tylenol, fwiw.
posted by gaspode at 2:52 PM on March 1, 2017

My husband takes medication that does not great things to his liver. He has been told not to take acetaminophen.
posted by sciencegeek at 3:16 PM on March 1, 2017

Hi, I'm a toxicologist. Any drug, over the counter or prescription, will cause some generally predictable changes in bloodwork results. The relative importance of these changes depends on what your physician is looking for, how recently you had previous (or baseline) bloodwork, and a few other details. When you call to schedule your physical, you should ask for your doctor's advice on the matter. It may not matter for their purposes, but you won't know until you bring it up.
posted by late afternoon dreaming hotel at 3:24 PM on March 1, 2017 [3 favorites]

Switch to ibuprofen if you have no contraindications to NSAIDs. It works better than Tylenol for dental pain.
posted by killdevil at 5:56 PM on March 1, 2017

Killdevil and Jim have it right, Tylenol is not an anti-inflammatory, so it does very little to alleviate most dental pain. Switch to NSAIDS if you can tolerate them, or better yet, ask your dentist what they recommend.
I am a dentist (though not your dentist obvs.) I would suggest naprosyn (an nsaid) and antibiotics if indicated, but never tylenol beyond what's already in mild narcotic pain meds.
Call the lab or the doc ordering the bloodwork and ask how quickly the tylenol will clear.
posted by OHenryPacey at 10:43 PM on March 1, 2017

Response by poster: To hopefully ease your minds, there was a single incident with St. John's Wort several years ago, all my doctors know about it (including pdoc), I've never been warned off Tylenol, and subsequent liver labs have been normal. There's no reason to expect anything terrible from taking standard amounts of Tylenol, I just want to make sure I'm keeping an accurate eye on any side effects from the antidepressant. If anything, my doctor thinks I'm being overly cautious, the chances of liver problems with this drug are low, but I will call her up and discuss the combining of drugs and timing of bloodwork. Thanks for your concern and advice, everyone!
posted by Dr. Sock, WebMD at 2:48 PM on March 2, 2017