There's no simple way to know how a drug will affect someone. Drugs affect people differently, nobody's experience is exactly the same. Even taking the same drug on a different occasion can affect someone differently.

Some of the reasons why drugs affect people differently from time to time and from person to person include the following factors:

1. The Drug
2. The Person
3. The Place

1. The Drug

Drugs have different effects on the body. Most drugs can be split into 3 types.

Stimulant drugs increase your heart rate, your blood pressure and breathing rate. Stimulant drugs can also make you feel alert, keep you awake and stop you from feeling hungry. They can also give you a feeling of confidence and increase your levels of energy. Cocaine is an example of a stimulant drug. The strong stimulant effects of cocaine can cause perfectly fit, young people to have heart attacks! Some other stimulant drugs include Ecstasy, Amphetamines and Nicotine.

Depressant drugs have the opposite effect from stimulant drugs. They slow down your breathing and heart rate. They can make you feel drowsy and relaxed. People are at risk of overdosing when using depressant drugs. This is because depressant drugs are basically slowing and shuting down your breathing and heart rate. Some depressant drugs include Alcohol, Heroin and Volatile Substances.

Hallucinogenic drugs affect the way you experience the world around you. This means the drug can affect your awareness and how you understand and experience what's happening around you. It can also affect your thoughts and feelings. Hallucinogenic drugs like Cannabis have been linked with feelings of paranoia and mental health problems. Some other hallucinogenic drugs include Ketamine and LSD.

When choosing which drug to take some people may consider the effect that it will have on them. "Will it make me speedy? Will it make me chilled out?" But knowing exactly what drug is being taken is never guaranteed. Someone may have been told that they have been given E and be expecting an all night dancing session in the club but in fact they have been given Ketamine! They have no way of really knowing what they have taken or the effect it will have on them and this can mean they lose some control.

Some other factors people should consider include: 

• How much of the drug they take
• How often they take it (e.g. every day, once a week)
• The strength of the drug
• The purity of the drug - drugs are often cut with other substances making it hard to know how weak or strong they are. People can never really be sure what they're taking!
• Mixing one drug with another- mixing drugs with alcohol or other drugs changes the effects they will have on people and increases their risk of harm.
• How the drug is taken- Is it snorted? Injected? Smoked/Inhaled? or Swallowed? - injecting is particularly dangerous as it is easier to overdose and there is the added risk of catching HIV and hepatitis if clean injecting equipment is not used.

2. The Person

Drugs affect everyone differently and can even have different effects on the same person if they try the same drug at another time. What makes us who we are? For example, our weight, our height, whether we're male or female all counts when it comes to taking drugs.

Here are some factors people should consider:

• Gender- drugs affect men and women differently
• Weight
• Age
• Height
• Have they used the drug before? - If they haven't it is difficult for them to know what to expect. It is easier for them to get into problems if they are inexperienced because they may expect the drug to work differently or they may take too much.
• Mood - what they experience from a drug will be affected by their mood at the time, particularly with hallucinogens like LSD and magic mushrooms. If they take drugs when they are feeling down or anxious, the drugs will probably make them feel worse. If they are in a good mood then drugs may enhanced this feeling.
• Health - using drugs is extra risky for people who have epilepsy, asthma, diabetes and heart or liver problems. It's also best for people to avoid drugs and alcohol if they are being treated for depression or if they are feeling anxious or worried.

3. The Place

Someone deciding upon which drug to take is one thing but where will they be when it starts to take effect? Will they be on their own? In a club? With people they don't know? When taking drugs it's important for people to think about where they will be and who they will be with. It could mean the difference from them enjoying their night or it ending in tears!

When taking drugs people should think about some of the following: 

• Are they alone? What if something goes wrong, or they have a bad experience?
• Are they with friends?
• Are they with strangers?
• Are they in a relaxed or threatening place?
• Are they out clubbing?
• Are they at a music festival?
• Are they driving?
• Are they having sex?

Taking drugs might make people more vulnerable to accidents or violence. People should be aware of where they are, who they're with and what's going on around them. They should take care in city centres at night, remembering the traffic can be very busy with lots of people on the streets, many of whom are intoxicated.

People using drugs or alcohol are less likely to use condoms when having sex, which increases the risk of getting infections like Chlamydia or HIV and unwanted pregnancies. They may even end up sleeping with someone that they don't even like and regret it. For more information on safer sex visit our Sex & Drugs section or www.swish.org.uk (Health promotion sexual health website).