Disregard Everything I Say

This article is going to serve as my attempt at writing a comprehensive break down and comparison guide for the universally felt subjective effects found within the two most commonly used deliriants. Including a basic run down of the drug itself and its chemistry. The guide for deliriants in general can be found here and includes a very detailed description of this particular class of hallucinogen. 
These two specific deliriants include Datura and DPH. The reason I am not writing an individual guide for each substance is that they do not seem to vary enough in terms of visual hallucinatory effects to warrant it, instead differing in their alternate styles of body high, dysphoria and head space. Which I will now begin to break down…

DPH (Diphenhydramine):

Onset : 60 - 120 minutes
Duration : 4 - 8 hours
Normal After Effects : up to 8 hours

DPH (Diphenhydramine) is a completely legal, freely available over the counter first-generation antihistamine possessing anticholinergic and sedative properties. It was one of the first known antihistamines, invented in 1943 by Dr. George Rieveschl. Usually sold under the brand name of “benadryl”. It is also available in many forms of many generic or store brand medication which are mainly used to treat allergies. Taken in “recreational” doses however, DPH  becomes an extremely powerful deliriant. 

In terms of it’s subjective effects the DPH trip is unlike anything found within psychedelics or dissociatives. It is not like other drugs in sense of dosage, a light dose does not equal a light trip. Doses under 300mg induce more of a restless feeling, body high, and muscle relaxation. Doses typically 600mg+ are what make the user enter delirium and begin to see fully formed hallucinations. Anything in between these two extremes is often a disappointing and uncomfortable experience, characterized with twitching and only very minor hallucinations, mostly in the peripheral vision.
The physical transition from reality to delirium is an extremely uncomfortable one, with the first noticeable sensation being that of having an extremely heavy body, as if the gravity has been multiplied by a thousand. Combined with muscle cramps, nausea, dizziness, drowsiness, restless leg syndrome, extreme dehydration and a sometimes painfully irregular heart beat. Users also commonly report all encompassing and painful jolts of electricity that spontaneously manifest themselves in a similar rhythm to hiccups. A frequent need to urinate also tends to painfully conflict with a feeling of concrete blocking your urethra. 
Thought patterns are also generally negative and dysphoric throughout the trip, generally consisting of extreme paranoia and feelings of impending doom. Feelings of being unable to communicate or understand normal language also become apparent. 
The levels of dysphoria experienced however, vary between people, with a very few users reporting that they do not seem to experience them at all. The hallucinations themselves however eventually become elaborate enough to cause the tripper to completely forget how terrible they are feeling. They are often extremely interesting. Manifesting themselves as completely concrete forms that are indistinguishable from reality in the trippers delirious state. Varying from mundane, to fascinating and to horrifying nightmarish experiences.

If you want to try DPH it is extremely easy to find as an over the counter sleep and allergy aid in most countries around the world. It is also available in bulk amounts for extremely cheap prices on amazon. Genuinely useful as a sleep aid, a dream enhancer and a potentiator of weed in low doses. It can become fatal if amounts close to or exceeding 2 grams are consumed and can result in death when combined with most stimulants and MAOI inhibitors.

Datura:

Onset : 60 - 120 minutes
Duration : 8 - 18 hours
Normal After Effects : up to 3 days

Datura is a genus of legal flowering plants that contains two psychoactive chemicals in roughly equal amounts. These are known as Scopolamine and Atropine, two molecules that are both in the tropane alkaloid class, with anticholinergic effects. The plants precise and natural distribution seems to be throughout most of the temperate and tropical regions of the globe, owing to its extensive cultivation and naturalization. There are a total of nine different species in the Datura genus, but the two most well-known species are Datura inoxia and Datura strammonium. Both of which have been used in a shamanic context for religious purposes on most continents since before recorded history began, with records of its use being found throughout the ancient americas, europe and india.

In terms of it’s subjective effects the Datura trip is extremely similar to that of DPH with a significantly longer duration but less dysphoria. The mental transition from reality to delirium is an extremely smooth one, a stuporous, hazy, mildly dissociating, light and floaty high is felt, and everything seems almost normal apart from waves of mild to intense paranoia. Feelings of being unable to communicate or understand normal language also become apparent with higher doses. 
Although Datura is not nearly as dysphoric as DPH it is still capable of feeling overwhelmingly unpleasant. With extreme dry mouth, hot / cold flushes and the inability to urinate despite desperately needing to all commonly reported throughout the trip. Blurred vision occasionally occurs, blinding the tripper and rarely but occasionally lasting for days to weeks after wards.
After a while, delirium takes over, causing you get used to the feeling and not notice it any more, or perhaps it genuinely fades. Leaving the trippers to experience concrete and 100% convincing visual and auditory hallucinations that can vary from mundane, to fascinating to horrifying. 

You can use Datura in many ways, one of the most common ways is to smoke the leaves and flowers, which offers a very mild trip with a duration similar to that of weed. You can also make a tea out of the leaves, flowers, and seeds, or you can eat the seeds with or without cooking them. Eating raw seeds is not recommended because of the high toxicity of them. The most potent parts in decreasing order are respectively the seed pods, leafs and flowers. Seeds are eaten while leaves are usually brewed as tea, though they are also chewed for their effects. 
It is extremely important to note however that the potency of plants varies wildly and there is no way for the common man to accurately measure the dosage. At high enough doses Datura becomes an incredibly toxic poison that can easily result in death, making Datura the most dangerous hallucinogen out there with accidental overdoses resulting in hospitalization not unheard of. The safest way to ensure this does not happen is to grind the dried plant matter into an extremely fine and even powder so that the active chemicals within them are distributed evenly across itself. From here you can slowly work your way up in extremely small increments until the correct dosage for that particular plant is found.
If you want to try Datura despite all of its risks, you can grow it yourself using seeds purchased online or find a wild plant in your local area.

Conclusion:
There is little to no insight to be gained from either of these substances and they can be extremely dangerous both physically and mentally if dosage is not payed close attention to. I would not recommend either of these drugs to any human being alive but view them more as drugs of interest than anything. Something that a person tries even if only once, just to see what they are like. Nobody is going to stop you from trying these substances, even our nations governments have deemed these substances as legally acceptable, whilst still prohibiting the use and sale of physically benign and mentally beneficial hallucinogens such as LSD or mushrooms. Keep in mind however, that you and you alone are responsible for your actions and that almost everybody who tries these drugs regrets it immediately.