Xanax “bars” are 2 mg rectangular white tablets of alprazolam, a benzodiazepine drug. These tablets also come in different colors such as green and yellow pills. The most common way to use Xanax bars is orally, by letting the pill dissolve underneath the tongue. By using one of these methods, a person’s system absorbs the most Xanax. Xanax (alprazolam) is prescribed for severe cases of anxiety and panic attacks, but people who take it without these issues may take the drug without a prescription for its soothing properties. With regular use, Xanax bars can cause a person to develop a tolerance. It means that to relax to the same level, their body requires more Xanax. For this reason, doctors advise withdrawing from Xanax rather than stopping it suddenly. A person’s brain chemistry starts to alter when they use Xanax. Gamma-aminobutyric acid (GABA) is naturally produced by the brain; however, taking Xanax may lead the brain to create less GABA to counteract the drug’s effects. Usually, the medicine starts working in the human body within an hour of use.