The impact that a drug can have on a person can depend on a number of factors. One of those factors is the use. If they are using the drug for recreational purposes and only in taking the drug ever so often, it may not impact their life at all.
It could have a positive impact, as it helps a person focus on their work more or relieve their body from pain. The negative impacts on drugs come when a person becomes addicted to it. Instead of it being taken for leisure when a person is addicted, their body feeds off the drug, and they are unable to function without it.
Drugs can often make you act differently and feel differently, as they alter the natural state of the body. You might also struggle with your actions and thoughts, depending on what type of drug it is and the strength used. If drugs begin to affect you negatively, it might end up costing you more than you can afford to lose. You might consistently, for weeks on end, show up to work late or not show up at all.
This behavior will prohibit earnings, which means you run the risk of not being able to afford groceries, your car, or phone payments, or you could even cease being able to pay for your living arrangements. Drugs can also be detrimental when it comes to nurturing your relationships. Your family and friends might see you acting differently toward them or in general, and this will make them wonder what happened to the person they love.