Diphenhydramine (Benadryl) is a first generation OTC antihistamine drug approved by the FDA in 1946. It is also used as a sleep aid, and for treatment of nausea, vomiting, and motion sickness. Despite its age, diphenhydramine is still one of the most effective and fast-acting antihistamines available with or without a prescription.

When taken with DXM, it can make DXM feel stronger, and reduce nausea and vomiting caused by syrup. For alleviating nausea take 25mg 30 minutes before taking DXM.

Warning Tylenol PM, Nyquil, and other medicines with diphenhydramine and acetaminophen can be fatal if taken in moderate to large quantities. Buy products, like Benadryl, that contain only diphenhydramine.

Contents
1Effects 2Combined With DXM 2.1As a DXM Booster 3Long term use 4Overdose 5Dangerous combinations

[top]Effects

At low doses (25mg to 75mg depending on tolerance):
- sedation
- music euphoria
- dry mouth
- increased urination
- feeling of dryness
- a wicked buzz
- decreased nausea
- mental fogginess
- incredible horniness
- lack of attention span

At higher doses (above 75 or 100mg) the effects begin to include:
- delirium and fever-like hallucinations (hallucinations that are not distinguishable from reality--you don't realize you're imagining things)
- getting into conversations with people who are not there
- rapidly cycling between hallucinations and relative normality
- seeing insects
- seeing strange shadows out of the corner of your eye
- extreme confusion
- itchy skin
- irregular heartbeat
- excitability/hyperactivity

[top]Combined With DXM

At recommended dosage Diphenhydramine can be useful in helping DXM users control nausea, eliminate allergic reactions, act as a mild booster (when taken 15-45 minutes before DXM), and aid in sleeping after a trip.

[top]As a DXM Booster

It works as mild booster because it is metabolized by the same liver enzymes DXM is, CYP2D6 & CYP3A4. The compete for them slowing the elimination of both drugs from your body & increasing blood levels as absorption rate is not slowed. It is important to remember that not just DXM/DXO levels are boosted but also Diphenhydramine, so a small to moderate dose can have greater effects than intended, specifically sedation. It doesn't take much Diphenhydramine to change the feel of the trip.

Because of this it is a bad idea to take diphenhydramine after taking DXM; the DXM will use up your body's ability to process the diphenhydramine, and a small dose of diphenhydramine will feel like a large dose of diphenhydramine.

[top]Long term use

As an anticholinergic, drug long term high dosage use can be detrimental to mental health. Searching the forums will produce plenty of anecdotal confirmations of this. In short it harms memory and impairs cognition for a few months.

[top]Overdose

Requires hundreds of mg, although not fatal in most cases it can be extremely unpleasant, both physically and mentally. A nasty combination. Do your best to avoid this, it's really the worst.

[top]Dangerous combinations

Diphenhydramine plus any one of these will make you feel like you might die, or at least want to:
- Large amounts of DXM
- Large amounts of alcohol
- Acetaminophen (only dangerous because of the acetaminophen)