Blood thinners and Mohs: the medication list nobody asks you for correctly

Every Mohs patient gets a version of the same phone call before the procedure, and it usually contains the same question: are you on any blood thinners. It is the right question asked in the wrong shape, because the answer most people give is either yes and the name of one prescription, or no. Both answers routinely miss the things that actually matter.

Two facts sit underneath this. The first is that the modern default in dermatologic surgery is to continue medically necessary anticoagulants and antiplatelets through the procedure rather than stopping them. The second is that the biggest source of avoidable harm around this is not bleeding during surgery, it is patients stopping their own medication because they assumed they should.

The original element in this piece is a structured inventory. Below is a five-tier medication list built specifically for the Mohs pre-operative call, organized so that the tiers people forget come first rather than last, plus what each tier changes and what it does not. It is designed to be filled out at your kitchen table before the phone rings.

Why the default is to continue. Mohs is performed on the skin under local anesthetic, with the surgical field visible and directly compressible throughout. Bleeding that occurs can be seen and controlled. The complication being prevented by an anticoagulant, on the other hand, is a stroke, a pulmonary embolism, or a stent thrombosis, none of which are visible or compressible and all of which are catastrophic. That asymmetry drives the practice.

The evidence supports it. A prospective evaluation of dermatologic surgery complications, including patients on multiple antiplatelet and anticoagulant medications simultaneously, examined this population directly (J Am Acad Dermatol, 2011). More recent work has continued to refine where the real risk concentrates, finding increased bleeding complications specifically after certain complex flap repairs in patients on combined antiplatelet and anticoagulation therapy (J Am Acad Dermatol, 2026). Note the shape of that finding: the risk clustered around a particular reconstruction type and a particular combination, not around anticoagulation in general. Other work has looked at factors like preoperative blood pressure and their influence on postoperative bleeding after Mohs, which is a reminder that medication is one input among several (Proc Bayl Univ Med Cent, 2025).

The five-tier inventory. Work through these in order. Tier one is the one everyone gets right. Tiers two through five are where the useful information hides.

Tier one, prescribed anticoagulants. Warfarin, and the direct oral anticoagulants such as apixaban, rivaroxaban, edoxaban, and dabigatran. For each, write the name, the dose, the timing, and critically, the reason it was prescribed. Atrial fibrillation, a mechanical heart valve, a previous clot, and a recent stent are different risk situations, and the reason matters more than the drug name. If you are on warfarin, note when your last INR was checked and what it was.

Tier two, prescribed antiplatelets. Clopidogrel, ticagrelor, prasugrel, and dipyridamole. These are frequently missed because patients do not classify them as blood thinners. If you have had a cardiac stent, note when, because the timing since stent placement is one of the most important pieces of information in this entire inventory.

Tier three, aspirin, and the distinction that matters. There are two entirely different aspirin situations and they get conflated constantly. Low-dose aspirin prescribed after a heart attack, stroke, stent, or bypass is a medically necessary antiplatelet and belongs in tier two in everything but name. Aspirin taken by choice for general prevention, or taken as a painkiller, is a different matter with a different risk calculation. Write down which one you are, and if you are not sure, that uncertainty is itself worth reporting.

Tier four, over-the-counter analgesics and cold remedies. Ibuprofen, naproxen, and other non-steroidal anti-inflammatories affect platelet function. Most people do not think of a painkiller taken twice a week for a bad knee as relevant to surgery, and combination cold and flu products often contain agents nobody registers. Write down anything taken in the two weeks before the procedure, including the occasional ones.

Tier five, supplements. This is the tier that is almost never volunteered and it is worth being thorough about. Fish oil and high-dose omega-3, vitamin E, ginkgo, garlic supplements, ginseng, turmeric and curcumin at supplement doses, and high-dose vitamin C all have plausible or documented effects on bleeding. So do some herbal sleep and joint preparations with long ingredient lists. The practical instruction: bring the actual bottles or photograph the ingredient panels rather than trying to recall names.

The rule that overrides everything else. Do not stop anything on your own. Not the aspirin, not the clopidogrel, not the apixaban, and not on the basis of anything you have read here or anywhere else. The decision to hold a medically necessary blood thinner belongs to the clinician who prescribed it, in conversation with the surgeon, and in most cases the decision will be to continue. Patients who quietly stop a cardiac medication for a week to be safe before a skin procedure are creating exactly the risk the medication exists to prevent.

What actually changes when you do disclose. Usually not whether the surgery happens. What it changes is the planning around it. It can influence how the wound is closed, since a simple linear repair, a graft, and a complex flap are not equivalent bleeding propositions, and this connects directly to the reconstruction options discussed after the tumor is clear. It changes how long you are observed afterward, how the pressure dressing is applied, and how detailed the post-operative bleeding instructions are. It can influence scheduling, since a case with higher bleeding risk is better placed earlier in the day than at five in the afternoon. And it changes what your surgeon watches for, which is the whole point.

What the studies do not tell you. Two honest gaps. First, most of the published evidence predates or only partially covers the direct oral anticoagulants, which now make up a large share of prescriptions and behave differently from warfarin in ways that matter for timing. The evidence base is thinner for exactly the drugs most new patients are on. Second, and more starkly, the supplement question is almost entirely uncharacterized in this surgical setting. The concern about fish oil and vitamin E rests on their effects on platelet function rather than on any trial of Mohs outcomes, because that trial has never been done. So the advice you get about supplements varies between practices, and that variation reflects genuine uncertainty rather than carelessness. Be thorough in disclosing them and expect the answer to be a judgment call.

Practical notes for the call itself. Have the inventory written before you dial rather than assembling it while someone waits. Include the prescriber's name for tier one and two items, because coordination between the dermatologic surgeon and a cardiologist or haematologist is sometimes needed and it is faster when the contact is already on the page. If your procedure is on a high-risk site such as the scalp, the nose, or the lower leg, mention that you know it is, because location changes both the reconstruction and the bleeding picture.

This inventory belongs alongside the rest of your preparation for the procedure, and the medication question is worth adding to the list you bring to the consultation rather than waiting for the pre-operative call to raise it. For the broader picture of what can go wrong and how often, the risks and complications of the procedure are worth reading in full.

The line worth remembering: in Mohs surgery, the dangerous decision is almost never continuing your blood thinner. It is stopping it without telling anyone.