A bad trip is defined as a trip, or stage of trip, which is disturbing and negative for the user. The most common manifestation of a bad trip is through negative thought loops; a user has a negative thought which they cannot let go of, and continues in a positive feedback loop becoming more negative. These can be triggered by ongoing life issues, a poor setting, or something as simple as worrying about having a bad trip.
The primary causes of a bad trip are entering the trip with a bad mindset. It's often repeated, but set and setting are the most important factors which will dictate the quality of a trip.
Tripping while in a bad mood, or in an unstable mental state is likely to lead to negative thoughts and thereby a bad trip. Similarly, tripping in an uncomfortable environment, such as with people you don't know well, is liable to lead to negative thoughts.
If it's your first time taking a new drug, it's always recommended to do so in the presence of a sober sitter - preferably one with experience in the given drug. Human contact can help reconnect a user to reality, and allay any paranoias.
Some chemicals are particularly given to causing bad trips; for example, deliriants such as DPH are notorious for causing bad trips due to the scary nature of their hallucinations, and inability for the user to distinguish the effects of the drug from reality. It is recommended to avoid such drugs.
Most bad trips are very similar to anxiety or panic attacks, and can be reversed by focusing on something positive, distracting yourself with some sort of entertainment or changing your setting. Something as simple as changing to another chair or putting on your favorite sweater can do the trick.
However, attempting to fight a bad experience is often liable to worsen things. It's helpful to focus on specific aspects that are discomforting and attempt to resolve them one at a time. You can start with easily solved issues of physical discomfort. Are you thirsty? Do you need to eat something? Having beverages and easy to eat foods like fruit can be very helpful. It's also useful to change your setting to change your mental state. If you have somber music playing, you can put on something more light hearted or energetic. If things are feeling overwhelming, it can help to lie down and try to reduce the amount of input you have to deal with.
Keep in mind that your experience will end, and that it's all a matter of time. Many bad trip situations are very similar to panic attacks, and as such the same techniques can be applied; mindfulness meditation and controlled breathing can help you calm yourself down.
Breathe slowly and deeply. Inhale through the nose for four seconds, hold the breath for four seconds, then take another four seconds to exhale through the mouth, hold the breath for 2 seconds and repeat. This can help relax you and clear your mind when you're having a panic attack.
Wrapping yourself in a blanket/duvet, the heavier the better, can provide a lot of comfort.
Don't be discouraged that you have somehow 'ruined' your high. The more challenging experiences tend to be some of the most insightful ones. If you try to analyse if it's going bad or well it's easy to get into a reinforcing loop if you are feeling poorly. Focus on what you feel and what you are thinking, so that later on you can go over those feelings and thoughts to gain insight as to your thought processes.
You may have come to the same conclusion many others have - that benzodiazepines or antipsychotics are great and will effectively end the trip, but really ought to only be a last resort. You can draw a parallel outside of the context of illegal drug use to those that drink heavily when times get tough. Instead of dealing with the hurdles that life presents they retreat to the bar.
Sometimes, just talking to someone can help change the course of a bad trip. For this purpose, TripSit provides a 24 hour tripsitting service you can find here. Come and say hi or type ~tripsit and we will be happy to talk with you!