Statins work on the liver, not on your blood

Cholesterol is a waxy, fat-like substance in every cell in your body, and you
need some of it. The problem is surplus: too much in the blood and it sticks
to artery walls, narrowing them and eventually blocking them, which is the
road to coronary artery disease.

Your liver makes it. It then travels on proteins called lipoproteins, and
the two that matter have opposite jobs:

Hold on to the fact that the liver is at both ends of that story, because it
explains everything a statin does.

What a statin actually does

A statin does not clean the blood. It works on the liver, in two directions
at once:

1. Slows production — the liver makes less cholesterol.
2. Increases removal — the liver gets better at pulling LDL that is
   already circulating back out of the blood.

The result is less plaque forming in the arteries, and studies show statins
lower the risk of heart attack and stroke in people with high LDL. They
also lower triglycerides, another blood fat that raises heart-disease risk,
and may raise HDL.

Statins are prescribed when high cholesterol has not come down enough with
lifestyle changes, and they are the most common medicine used for it.

The risks, in proportion

Statins usually cause no side effects. The ones that exist are worth stating
precisely rather than vaguely, because vague versions are what make people
stop taking them:

• Type 2 diabetes — a real raised risk, but mainly in people already at
  high risk: those who are overweight or have obesity, prediabetes or
  metabolic syndrome.
• Abnormal liver enzyme tests — common enough to see on a blood test.
  Actual liver damage is very rare.
• Muscle damage — uncommon. In rare cases it leads to muscle pain and
  kidney damage. If muscle pain starts, a blood test looks for damage; the
  pain often goes away on a different statin, and muscles may heal after the
  switch.

Statins should not be taken in pregnancy or while breastfeeding, and are not
recommended with certain liver diseases.

The one rule that matters most

Do not stop on your own. Stopping a statin without talking to your
provider can lead to a serious problem and, in rare cases, death. If you want
to stop or change, that is a conversation, not a decision to make alone.

Two practical points follow from the liver being the target. Ask which
medicines, supplements and foods to avoid — some interact badly, and some
make the statin less effective. And grapefruit, fresh or as juice, changes
how the liver breaks down some statins. It is not folklore; it is the same
mechanism the drug is using.

Source: MedlinePlus, U.S. National Library of Medicine.