Statins are known to cause some liver damage (hence the need to measure liver enzymes every few months), muscle damage (myositis or muscle inflammation, and in severe cases rhabdomyolysis or break down of muscle tissue) which we think of should the patient report severe muscle and joint pain, and last but not least, statins may lead to the development of type 2 (insulin dependent) diabetes but in a smaller percentage of people, and usually these people have a propensity to develop diabetes (they have risk factors such as a family history of diabetes, they struggle with obesity etc.)
Reports about impaired memory function are sporadic and not fully elucidated, and vary among those who actually experience them in terms of the timing of onset of symptoms in relation to the duration of use of the medication.
Concerning sexual dysfunction associated with the use of statins, no well established evidence so far exists to confidently confirm this complication.
Alternatives? Well, so far, none. In cases of dyslipidemia (elevated cholesterol levels), statins are use as adjunct treatment to lifestyle modifications (diet and regular exercise) when these alone fail to reduce cholesterol levels, especially in the context of inherited dyslipidemias. The main target is to confer protection against the development of atherosclerotic vascular disease due to hypercholesterolemia.