Quoting Wikipedia:

The mental effects are described by many as "dreaming while awake" involving visual and auditory hallucinations which, unlike those experienced with most psychedelics, often cannot be readily distinguished from reality. Many users report a side effect profile consistent with tropane glycoalkaloidal poisoning. This is due to antagonism of muscarinic acetylcholine receptors in both the central and autonomic nervous system, inhibiting various signal transduction pathways. In the CNS, diphenhydramine readily crosses the blood-brain barrier, exerting effects within the visual and auditory cortex, accounting for reported visual and auditory disturbances. Other CNS effects occur within the limbic system and hippocampus, causing confusion and temporary amnesia. Toxicology also manifests in the autonomic nervous system, primarily at the neuromuscular junction, resulting in ataxia and extrapyramidal side-effects, and at sympathetic post-ganglionic junctions, causing urinary retention, pupil dialation, tachycardia, irregular urination, and dry skin and mucous membranes. Considerable overdosage can lead to myocardial infarction, serious ventricular dysrhythmias, coma and death. Such a side-effect profile is thought to give ethanolamine-class antihistamines a relatively low abuse liability.
In my conclusion, it will make you have a scary ass trip with no ability to differ reality from fiction. It can completely trick your mind, and from what I know, it can be a very unpredictable drug. Imaginary example:

Let's say I were to take 200mg on Tuesday. Two hours later, I feel nothing but light sedation and confusion. Two days later, I take the same dose. An hour later, I'm talking to people that aren't there, talking to trees, and forget who I am. Very hard to conclude what will happen with this drug.

I suggest you try the recommended dose first to make sure you aren't allergic. If you don't have any adverse side effects, wait about two days and try doing about five times the normal dose. You may or may not get something. I really don't advise you to mess with this drug all actually, but I'm supplying you with information just so you don't do anything drastic. Remember that it can be a very frightening trip, and you probably won't like it at all. But if you end up wanting to... to each his own.

Besides, even though I didn't like my experience, I'm actually willing to try it again. I might post back and show you a good example on what could happen if I get a chance with some.