This is the question asked by the American Chiropractic Association. And this is their answer [the numbers in square brackets were inserted by me and refer to my comments below]:
Chiropractic is widely recognized  as one of the safest drug-free, non-invasive therapies available for the treatment of neuromusculoskeletal complaints . Although chiropractic has an excellent safety record , no health treatment is completely free of potential adverse effects. The risks associated with chiropractic, however, are very small . Many patients feel immediate relief following chiropractic treatment , but some may experience mild soreness, stiffness or aching, just as they do after some forms of exercise . Current research shows that minor discomfort or soreness following spinal manipulation typically fades within 24 hours …
Some reports have associated high-velocity upper neck manipulation with a certain rare kind of stroke, or vertebral artery dissection . However, evidence suggests that this type of arterial injury often takes place spontaneously in patients who have pre-existing arterial disease . These dissections have been associated with everyday activities such as turning the head while driving, swimming, or having a shampoo in a hair salon . Patients with this condition may experience neck pain and headache that leads them to seek professional care—often at the office of a doctor of chiropractic or family physician—but that care is not the cause of the injury. The best evidence indicates that the incidence of artery injuries associated with high-velocity upper neck manipulation is extremely rare—about one to three cases in 100,000 patients who get treated with a course of care . This is similar to the incidence of this type of stroke among the general population …
When discussing the risks of any health care procedure, it is important to look at that risk in comparison to other treatments available for the same condition . In this regard, the risks of serious complications from spinal manipulation for conditions such as neck pain and headache compare very favorably with even the most conservative care options. For example, the risks associated with some of the most common treatments for musculoskeletal pain—over-the-counter or prescription nonsteroidal anti-inflammatory drugs (NSAIDS) and prescription painkillers—are significantly greater than those of chiropractic manipulation …
Doctors of chiropractic are well trained professionals who provide patients with safe, effective care for a variety of common conditions. Their extensive education has prepared them to identify patients who have special risk factors  and to get those patients the most appropriate care, even if that requires referral to a medical specialist .
END OF QUOTE
- Appeal to tradition = fallacy
- …and every other condition that brings in cash.
- Not true.
- Probably not true.
- The plural of anecdote is anecdotes, not evidence.
- Not true, the adverse effects of spinal manipulation are different and more severe.
- Not true, they last 1-3 days.
- Not just ‘some reports’ but a few hundred.
- Which does not mean that spinal manipulation cannot provoke such events.
- True, but this does not mean that spinal manipulation cannot provoke such events.
- There are other estimates that gives much higher figures; without a proper monitoring system, nobody can provide an accurate incidence figure.
- Not true, see above.
- ‘Available’ is meaningless – ‘effective’ is what we need here.
- The difference between different treatments is not merely their safety but also their effectiveness; in the end it is the risk/benefit balance that determines their value.
- Not true, there are no good predictors to identify at-risk populations.
- Chiropractors are notoriously bad at referring to other healthcare professionals; they have a huge conflict of interest in keeping up their cash-flow.
So, is chiropractic a safe treatment?
My advice here is not to ask chiropractors but independent experts.