This information is for people who are at risk of getting post-traumatic stress disorder. It tells you about propanolol, a treatment used to prevent post-traumatic stress disorder. It is based on the best and most up-to-date research.
Does it work?
There's not enough research to show whether taking a drug called propranolol straight after you've gone through a frightening event will stop you getting post-traumatic stress disorder ( PTSD).
What is it?
Propranolol is a type of drug known as a beta-blocker. The brand name is Inderal or Inderal LA.
This drug is sometimes used to treat people who feel anxious. When you feel anxious your heart may beat fast and your palms may get sweaty. Beta-blockers can help get these symptoms under control.
Beta-blockers are also used to treat high blood pressure, heart failure, and a type of chest pain called angina.
How can it help?
Only one study has looked at propranolol for PTSD. It found the drug was no better than a dummy treatment (a placebo) at preventing PTSD.  There is no other evidence to show whether this drug can help.
How does it work?
Some researchers think that when you go through a frightening or shocking event, your body makes a large amount of a hormone called adrenaline.
This hormone affects the part of your brain that triggers emotions and memories, especially upsetting ones. Researchers think that this may cause PTSD.
Propranolol stops this hormone working. So the idea is that it may prevent PTSD. But so far there is no good evidence that proves that this is how propranolol works.
Can it be harmful?
The study we found didn't say whether the people who took propranolol had any side effects. 
But we know from other studies that beta-blockers like propranolol have many side effects. The most common ones are listed here.
They lower your blood pressure. This can make you feel dizzy if you stand up too fast. You may also get more tired than usual. If your blood pressure gets very low, you may faint.
Some men have difficulty getting an erection when they take beta-blockers.
If you have trouble breathing because you have asthma or bronchitis, you should not take beta-blockers.
How good is the research on taking propranolol to prevent PTSD?
We only found one study that looked at using propranolol to prevent post-traumatic stress disorder.  It found that the drug didn't help, but this study was not a particularly fair test of treatments, so it's hard to know if the results are reliable.