PrEP is a combination of HIV treatments and may have similar side effects. Some people might not have any symptoms while a few can experience severe symptoms. Most people will experience mild symptoms that usually last a few days to weeks and then go away. The most common symptoms are nausea, vomiting, diarrhea , tiredness, sleeplessness, dry mouth and headaches. Your prescribing health care provider should explain to you the possible side effects and things to look out for depending on your specific combination of HIV treatments.