How bad is crystal meth if a small amount is used two times per week? 
(Small = a thin line no longer than one inch long.)  I'm interested to
know the long term effects for a recreational user.

Hello,

With Crystal Meth, the side effects are more for the duration the meth
is in your body, not over time. it seems that most side effects
subside as it works it's way out of your system. Working it's way out
of you system can take weeks to months, depending on how heavy of a
user you are.

Some of the most common side effects of CM are Anxiety, insomnia,
emotional swings, paranoia, dry mouth, palpitations, body temperature
increases, along with breathing and heart rate. Blood pressure becomes
affected. People with cardiac and blood pressure problems can cause
further damage to their cardiovascular systems.

Symptoms increase with long-term use, and can involve paranoid
delusions and hallucinations. Violence and self-destructive behavior
are common. Overdose is also a risk with CM no matter what the dose,
is there is no regulated strength. Symptoms include fever,
convulsions, and coma. Death can result from burst blood vessels in
the brain (triggered by spikes in blood pressure) or heart failure.

Crystal meth can cause behavioral problems, paranoia and psychosis,
esp. in individuals with a predisposition to mental illness

So, it looks like the short and long term effects are not good. 

http://menshealth.about.com/cs/stds/a/crystal_meth.htm
http://www.doitnow.org/pages/523.html


If this answer requires further explanation, please request
clarification before rating it, and I'll be happy to look into this
further.
Nenna-GA
Google Answers Researcher

Also, I just wanted to briefly add, crystal meth is chemically very
similar to adrenaline, and it can cause severe heart problems, as well
as other neural effects.