In most cases, it is best to start with one drug, selecting the least toxic, and assessing its effectiveness fully before adding other drugs. If a treatment failure, consider discontinuing the present drug and switch to a new drug. If a partial response, consider augmentation by adding one or more augmenting drugs. Augmentation may be with a drug in a different class or a drug within the same class that has a complementary biological action. If the primary drug successfully treats a symptom cluster but leaves other symptom clusters untreated, consider combination treatment.
Combination is usually with a drug in a different class.
Add one medication at a time, define criteria, and wait to get a clear response. It is almost always best not to be pressured into rushing treatment by not completing adequate trials or adding multiple drugs together because it it then not possible to make any objective judgments about effectiveness. In complex and chronic cases, multiple drug treatment is common and often helpful. When communication with the person is severely impaired or non-existent, it is much more difficult to make a symptomatic diagnosis. In these cases, treatment is often directed more toward behavior and non-specific diagnoses.