Antihistamine Side Effects & Signs of Overdose

[Kayteex]

Hi,
So this week I've been taking Diphenhydramine, Doxylamine, Promethazine & Chlorpheniramine together (in a single dose) making a total of 400mg+ worth of antihistamines.

What I want to know is how you do know if you're suffering from side effects or if what you're experiencing is signs of an overdose?

This week I've suffered with the worst dry mouth ever to the point I've developed oral thrush.

I've experienced visual hallucinations, where I was talking to people who weren't even there although I was convinced there was.

I was seeing insects climbing the walls.I even moved the TV because I genuinely believed there was a mouse behind it. I even took photographs of the 'mouse' on my phone - what I thought was a mouses tail was actually a TV cable!

I was getting getting dressed and putting my make-up on to go out, I thought it was daytime. It was actually 3am! The fact is was dark outside didn't register with me. I was confused and slightly freaked out.

I was somewhat drowsy, but not as much due to tolerance.

I had extreme blurred vision with a total inability to focus on anything. I couldn't read or watch TV.

I had the usual urinary retention (not any more severe than usual - I just have to really push/strain to empty my bladder as well as the inability to feel when I need to go).

I didn't have the fast heart rate normally found in antihistamine overdoses because I was also taking opioids and beta-blockers in combination (so heart rate was slowed and blood pressure drops).

I also had many, many myoclonic jerks. I felt very warm as well although this didn't bother me as it usually would.

I don't know where the side effects end and the symptoms of overdose start?

 

[oxlong27]

These symptoms are to be expected if you take to many antihistamines. I wouldn't say you overdosed per-se but I would definitely discontinue or at least cut down dosage. I know people who have taken extreme doses of diphenhydramine and experienced severe delirium and talked to dead ppl etc. Everything else you mentioned are classic side effects. Dry mouth, urinary retention, weird vision. All to be expected

 

[d1nach]

Lol

The absolute maximum of benadyrl at one time is 125 mg orally or 50mg iv.

And thats for allergic reactions

What u have is called anticholinergic syndrome almost everyone of those drugs block receptors called muscarinic acetylcholine receptors

According to wiki

Possible effects of anticholinergics include:

Poor coordination
Dementia[13]
Decreased mucus production in the nose and throat; consequent dry, sore throat
Dry-mouth with possible acceleration of dental caries
Stopping of sweating; consequent decreased epidermal thermal dissipation leading to warm, blotchy, or red skin
Increased body temperature
Pupil dilation; consequent sensitivity to bright light (photophobia)
Loss of accommodation (loss of focusing ability, blurred vision – cycloplegia)
Double-vision
Increased heart rate
Tendency to be easily startled
Urinary retention
Diminished bowel movement, sometimes ileus (decreases motility via the vagus nerve)
Increased intraocular pressure; dangerous for people with narrow-angle glaucoma.
Possible effects in the central nervous system resemble those associated with delirium, and may include:

Confusion
Disorientation
Agitation
Euphoria or dysphoria
Respiratory depression
Memory problems[14]
Inability to concentrate
Wandering thoughts; inability to sustain a train of thought
Incoherent speech
Irritability
Mental confusion (brain fog)
Wakeful myoclonic jerking
Unusual sensitivity to sudden sounds
Illogical thinking
Photophobia
Visual disturbances
Periodic flashes of light
Periodic changes in visual field
Visual snow
Restricted or "tunnel vision"
Visual, auditory, or other sensory hallucinations
Warping or waving of surfaces and edges
Textured surfaces
"Dancing" lines; "spiders", insects; form constants
Lifelike objects indistinguishable from reality
Phantom smoking
Hallucinated presence of people not actually there
Rarely: seizures, coma, and death
Orthostatic hypotension (severe drop in systolic blood pressure when standing up suddenly) and significantly increased risk of falls in the elderly population.[15]
Older patients are at a higher risk of experiencing CNS sideffects due to lower acetylcholine production.

A common mnemonic for the main features of anticholinergic syndrome is the following:[16]

Blind as a bat (dilated pupils)
Red as a beet (vasodilation/flushing)
Hot as a hare (hyperthermia)
Dry as a bone (dry skin)
Mad as a hatter (hallucinations/agitation)
Bloated as a toad (ileus, urinary retention)
And the heart runs alone (tachycardia)

 

[d1nach]

Btw dont beat yourself up over it i did it to by accident so have most of my friends its a common mistake because often you can take multiple anticholinergics and none of them say they are.