Adverse effects
Adverse effect incidence:Uncommon (0.1–1% incidence) adverse effects include:

Dry mouth
Anhidrosis (reduced ability to sweat to cool off)
Tachycardia (usually occurs at higher doses and is succeeded by bradycardia)
Bradycardia
Urticaria (hives)
Pruritus (itching)Rare (<0.1% incidence) adverse effects include:

Constipation
Urinary retention
Hallucinations
Agitation
Confusion
Restlessness
SeizuresUnknown frequency adverse effects include:

Anaphylactic shock or reactions
Dyspnea (shortness of breath)
Rash
Erythema
Other hypersensitivity reactions
Blurred vision
Mydriasis (dilated pupils)
Drowsiness
Dizziness
Somnolence

Overdose
Physostigmine, a cholinergic drug that readily crosses the blood-brain barrier, has been used as an antidote to treat the central nervous system depression symptoms of a scopolamine overdose. Other than this supportive treatment, gastric lavage and induced emesis (vomiting) are usually recommended as treatments for oral overdoses. The symptoms of overdose include:
Tachycardia
Arrhythmia
Blurred vision
Photophobia
Urinary retention
Drowsiness or paradoxical reaction, which can present with hallucinations
Cheyne-Stokes respiration
Dry mouth
Skin reddening
Inhibition of gastrointestinal motility

Interactions
Due to interactions with metabolism of other drugs, scopolamine can cause significant unwanted side effects or unpredictable synergies when taken with other medications or compounds. Specific attention should be paid to other medications in the same pharmacologic class as scopolamine, also known as anticholinergics. These additional compounds could also potentially interact with the metabolism of scopolamine: receptor-binding analgesic/pain medication such as gabapentinoids or opioids, ethanol, cannabinoids, zolpidem, thiazide diuretics, nicotine, benzodiazepines, buprenorphine, and especially anticholinergic drugs such as tiotropium, diphenhydramine, dimenhydrinate, etc. Route of administration
Scopolamine can be taken by mouth, subcutaneously, in the eye, and intravenously, as well as via a transdermal patch. Pharmacokinetic
Scopolamine undergoes first-pass metabolism and about 2.6% is excreted unchanged in urine. Grapefruit juice decreases metabolism of scopolamine consequently increasing plasma concentration.
Australian bush medicine
A bush medicine developed by Aboriginal peoples of the eastern states of Australia from the soft corkwood tree (Duboisia myoporoides) was used by the Allies in World War II to stop soldiers from getting seasick when they sailed across the English Channel on their way to France during the Invasion of Normandy. Later, the same substance was found to be usable in the production of scopolamine and hyoscyamine, which are used in eye surgery, and a multimillion dollar industry was built in Queensland based on this substance. Recreational and religious use
While it has been occasionally used recreationally for its hallucinogenic properties, the experiences are often unpleasant, mentally and physically. It is also physically dangerous and officially classified as a deliriant drug, so repeated recreational use is rare. In June 2008, more than 20 people were hospitalized with psychosis in Norway after ingesting counterfeit rohypnol tablets containing scopolamine. In January 2018, 9 individuals were hospitalized in Perth, Western Australia, after reportedly ingesting scopolamine. However, the alkaloid scopolamine, when taken recreationally for its psychoactive effect is usually taken in the form of preparations from plants of the genera Datura or Brugmansia, often by adolescents or young adults in order to achieve hallucinations and an altered state of consciousness induced by muscarinic antagonism. In circumstances such as these, the intoxication is usually built on a synergistic, but even more toxic mixture of the additional alkaloids in the plants which includes atropine and hyoscyamine.