The clinical risks are the part CDC actually publishes on, and they are specific rather than general. CDC lists infection as inherent to any procedure, and names wound infections, bloodstream infections, donor-derived infections in transplantation or transfusion, and hepatitis B, hepatitis C and HIV among complications seen in procedures performed in other countries. It states that "[h]ighly drug-resistant bacteria and fungi have caused disease outbreaks among medical tourists" and that facilities elsewhere may not have adequate infection-control practices. On standards, its wording is careful and worth repeating exactly: "Some countries' requirements for maintaining licensure, credentialing, and accreditation may also be less than what would be required in the United States," and counterfeit medicines and lower-quality devices may be used in some countries. It also flags communication difficulties where the patient does not speak the language fluently, and blood clots after flying, advising that delaying air travel for 10 to 14 days after major surgery, particularly chest surgery, minimizes risks from pressure changes.
Continuity of care is where the financial exposure concentrates. CDC's point is not that complications are likely but that treating them happens at home: follow-up care "might be prolonged and might not be covered by your health insurance", and travelers "should understand the potential financial costs associated with follow-up care or emergency care in the event of complications, review their health insurance policies to determine what, if anything, is covered and plan for the possibility of paying for additional care out-of-pocket." CDC's own risk-reduction advice includes obtaining international travel health insurance that covers medical evacuation back to the United States, arranging domestic follow-up before traveling, checking the clinician's qualifications and the facility's accreditation through bodies such as Joint Commission International, and getting copies of all records from the destination facility before returning. It adds a caution against reading accreditation as a guarantee: "all surgeries carry the risk of complications and accreditation does not guarantee a positive outcome."
On the tax side, the sharpest distinction is one people routinely get backwards, and Publication 502 states it in two adjacent passages. For a drug taken while abroad: "You can include the cost of a prescribed drug you purchase and consume in another country if the drug is legal in both the other country and the United States." For the same drug brought home: "In general, you can't include in your medical expenses the cost of a prescribed drug brought in (or ordered and shipped) from another country. You can only include the cost of a drug that was imported legally." The place of consumption, not the place of purchase, is what separates the two answers.
Lodging is includible, conditionally and in a small amount, and this is where the phrase "medical tourism" collides with the rule. Section 213(d)(2) of the tax code treats lodging away from home as paid for medical care only where the lodging is not lavish or extravagant, is "primarily for and essential to" medical care, the care "is provided by a physician in a licensed hospital (or in a medical care facility which is related to, or the equivalent of, a licensed hospital)", and "there is no significant element of personal pleasure, recreation, or vacation in the travel away from home". The statute then caps it: the amount "shall not exceed $50 for each night for each individual." Publication 502 restates all four conditions, adds that lodging for a person traveling with the patient counts, so a parent accompanying a sick child can reach $100 a night, and says plainly that "[m]eals aren't included." That exclusion belongs to the lodging rule. Meals at a hospital or similar institution are a separate matter, includible where a principal reason for being there is to receive medical care.
Two consequences deserve stating rather than implying. The condition about personal pleasure, recreation or vacation is the one that most directly limits a trip structured as a vacation around a procedure, and Publication 502 separately states that a taxpayer "can't include in medical expenses a trip or vacation taken merely for a change in environment, improvement of morale, or general improvement of health, even if the trip is made on the advice of a doctor." Transportation is a different line item: amounts paid "for transportation primarily for and essential to medical care" are includible, including transportation to another city where the trip is primarily for and essential to receiving medical services. And neither section 213(d)(2) nor Publication 502's lodging discussion says how the licensed-hospital requirement applies to a facility licensed under another country's law, which leaves that an open question rather than a settled yes or no.
One category is closed outright. Publication 502 provides that "[y]ou can't include in medical expenses amounts you pay for illegal operations, treatments, or controlled substances whether rendered or prescribed by licensed or unlicensed practitioners." Publication 502 does not say whose law decides that a procedure is illegal, and the only version of the question it answers is the domestic one, ruling out controlled substances "that aren't legal under federal law, even if such substances are legalized by state law". Being lawful where the care was given is therefore not by itself an answer.
Whether any of this produces a deduction is a separate question governed by the medical expense deduction's own threshold, and the rules for reimbursing costs from a health savings account or flexible spending account start from the same statutory definition of medical care but diverge from the deduction in places, which qualified medical expenses covers.