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Q: Long term effects of taking common antihistamines ( Answered 5 out of 5 stars,   2 Comments )
Subject: Long term effects of taking common antihistamines
Category: Health > Medicine
Asked by: davecraze-ga
List Price: $50.00
Posted: 30 Jan 2006 13:19 PST
Expires: 01 Mar 2006 13:19 PST
Question ID: 439359
Long term effects of common antihistamines?

I have been taking diphenhydramine or doxylamine succinate on an
almost daily basis for years for my general inability to get to sleep.

Lately, I have been thinking about what, if anything, may be written
in the medical literature or other healthcare information regarding
taking these 2 OTC antihistamines on a daily basis as I do.

I would like to learn as much as I can about this topic.
Subject: Re: Long term effects of taking common antihistamines
Answered By: crabcakes-ga on 30 Jan 2006 16:44 PST
Rated:5 out of 5 stars
Hello Davecraze,

   First, I must address why you have been taking these OTC medicines
for so long. You can become dependant on these medications. One is
advised not to take these antihistamines for longer than a few weeks,
without being followed by your doctor, unless you use them
intermittently, and not nightly.

   You can also build up a resistance to these drugs, so they will no
longer be effective. I found no studies done on long term use, and
some sites state long term effects are unknown. I urge you to have a
complete examination by your doctor and discuss your sleeping problems
together. There may be an underlying problem such as depression, a
medical disorder, or other medications causing your sleeplessness, and
your doctor should be made aware of this.

However, you should not abruptly stop taking Benadryl and Unisom. Your
doctor will likely taper you off gradually, or prescribe medication to
help you.

?Most experts today recommend medications for insomnia only as a last
resort after behavioral techniques and lifestyle changes have not been
The National Sleep Foundation provides the following guidelines for
the use of medications to treat insomnia. Medications may be taken
?	The cause of insomnia has been identified and is best treated with medication. 
?	Sleep difficulties cause problems in accomplishing daily activities. 
?	Behavioral approaches have proven ineffective and the person is
unwilling to try them.
?	A person is suffering insomnia-related distress and beginning
behavioral therapy.
?	Insomnia is temporary or short-term. 
?	Insomnia is expected or occurs in association with a known medical
or biological condition (e.g. Premenstrual Syndrome) or an event such
as giving a speech or traveling across time zones.
Treatment with medications should: 
?	begin with the lowest possible effective dose, 
?	be short-term, if used nightly, 
?	be intermittent, if used long-term, and 
?	be used only in combination with good sleep practices and/or
behavioral approaches.
?The extended use of OTC sleep medications can exacerbate your
insomnia, and is not recommended. If you are experiencing chronic
insomnia, consult with your doctor to discuss other appropriate and
more-effective treatments.?

?It should be noted that the sleep experienced while taking OTC sleep
medications is not of the same quality as normal sleep. Some people
who take OTC sleep medications spend as little as 5% of their total
sleep time in deep sleep (compared to approximately 10-25% for healthy
OTC sleep medications should not be used by people with angina, heart
arrhythmias, glaucoma, prostrate problems or urinary problems.
Antihistamine is known to worsen these conditions. As with any
medication, it is advised that you consult with your doctor if you
have questions before taking OTC sleep medications.?

From Unisom?s own site:

?Are there any drug interactions with Unisom®?
If presently you are taking any other drug, please do not take Unisom®
without consulting your physician or pharmacist, who can best
determine if Unisom® would be appropriate with your medication

How long can I use Unisom®?
Unisom® can be used for up to 2 weeks. Stop use and ask a doctor if
sleeplessness persists continuously for more than 2 weeks. Insomnia
may be a symptom of serious underlying medical illness.

Is it possible to develop resistance or tolerance to Unisom®?
It is possible that after long-term use you may become resistant to
the sedation (sleepiness) from Unisom®. However, these products should
not be used for more than 14 days unless recommended by your doctor.

Is it possible to become ?addicted? to Unisom®?
We have no data to suggest that, when taken as directed, Unisom® is addictive.

?DRUG INTERACTIONS: Diphenhydramine adds to (exaggerates) the sedating
effects of alcohol and other drugs than can cause sedation such as the
benzodiazepine class of anti-anxiety drugs (e.g., Valium, Ativan,
Klonopin, Xanax), the narcotic class of pain medications and its
derivatives (e.g., Percocet, Vicodin, Dilaudid, Codeine, Darvon), the
tricyclic class of antidepressants (e.g., Elavil, Tofranil,
Norpramin), and certain antihypertensive medications (e.g., Catapres,
Inderal). Diphenhydramine can also intensify the drying effects of
other medications with anticholinergic properties (e.g., Bentyl,
Urecholine, Probanthine).?

?Don't use antihistamines for more than about 10 days or more than 2
or 3 times a year without consulting a doctor, who may diagnose a more
severe problem requiring other medication.?

?In addition, sleeping pills can become less effective after a while.
OTC sleep aids contain antihistamines to induce drowsiness. They're OK
for occasional sleepless nights, but they, too, often lose their
effectiveness the more you take them. Many sleeping pills contain
diphenhydramine, which can cause difficulty urinating and a drowsy
feeling in the daytime.?

The half life of diphenhydramine is 1 to 4 hours. That means that at 4
hours or so, half of the drug is cleared from your body. In another 4
hours, another half is cleared. You can see how this might make you
drowsy in the day time! Doxylamine succinate has an elimination
half-life of approximately 9 hours.

?Patients do say that antihistamines help them sleep better. This
effect is mild, but positive. Side effects, such as drowsiness during
the day, can be common and severe. The effectiveness when used over
time has not been studied. These medications may affect the activities
of patients the following day. This may lead to other problems.?

?Ask your doctor for an evaluation. Treatment is available ? but it
depends on what's causing your insomnia. For occasional sleepless
nights, sleeping pills may be helpful. Although sleeping pills don't
treat the underlying cause of insomnia, they may help you get some
much needed rest.?

??  Take it one day at a time. Sleeping pills are a temporary solution
for insomnia. Most over-the-counter varieties are intended to be used
for only two to three nights at a time. Taken too often, some sleeping
pills may cause rebound insomnia ? sleeplessness that returns in full
force when you stop taking the medication.
?  Avoid alcohol. Never mix alcohol and sleeping pills. Alcohol
increases the sedative effects of the pills. Even a small amount of
alcohol combined with sleeping pills can make you feel dizzy, confused
or faint.
?  Quit carefully. When you're ready to stop taking sleeping pills,
follow your doctor's instructions or the directions on the label. Some
medications must be stopped gradually.
?  Watch for side effects. If you feel sleepy or dizzy during the day,
talk to your doctor about changing the dosage or discontinuing the

?Sleep problems can worsen if not treated properly and promptly.
Self-medicating with over-the-counter medications can lead to adverse
effects or worsening of the insomnia. Improper assessment of a
patient's insomnia and its cause can also lead to unresolved problems.

Insomnia is an important condition that must be assessed and treated
appropriately in order to assure good long-term outcomes and avoid any
complications from the sleep disorder. A lack of sleep can cause the
patient to be fatigued and inattentive the next day. This may lead to
falls and injuries, which is of particular concern in the elderly.
Lack of sleep can also lead to falling asleep on the road and causing
a car accident, or being unable to pay attention at school or work and
therefore not being able to perform as well as one would expect. Even
more serious, insomnia can cause a patient to become overly stressed,
leading to depression, anxiety, or other mental illnesses. To make
matters worse, these same mental illnesses could be the cause of the
patient's insomnia, which are then exacerbated by the lack of sleep,
and lead to the formation of a vicious cycle.?

?When a medical condition is present along with insomnia, that
underlying condition should be treated first. By treating the
underlying problem, the insomnia should also be corrected. If it does
not, then another assessment should be done, including the patient's
sleep habits, and his or her treatment should be adjusted accordingly.
It would be optimal if the insomnia can be treated without any
pharmacologic intervention. Behavior modification, which will be
discussed in the next section, is a good way to correct many sleep
Please read the entire site for complete information. 

"These medications can be useful for short-term treatment of temporary
sleep problems. However, no studies demonstrate their long-term
effectiveness beyond 30 continuous nights. In addition, tolerance and
dependence develop rapidly."

"Tolerance, Dependence and Withdrawal Effects: Some tolerance may
develop to the sedative effects of diphenhydramine with repeated oral
dosing. No reported dependence or withdrawal effects with doses

Doxylamine Succinate (The ingredient in Unisom) -  ?The most common
side-effect is sedation, varying from slight drowsiness to deep sleep,
and including lassitude, dizziness and in-coordination. Other
side-effects include gastro-intestinal disturbances such as nausea,
vomiting, diarrhoea or constipation, anorexia or increased appetite
and epigastric pain. Doxylamine succinate may also produce
antimuscarinic effects including blurred vision, difficulty in
micturition, dysuria, dryness of the mouth and tightness of the chest.
Other central effects include hypotension, muscular weakness,
tinnitus, euphoria or depression, headache, irritability and

Paradoxical central nervous system stimulation may occur with
insomnia, nervousness, tachycardia, tremors and convulsions.
Doxylamine succinate may precipitate epileptiform seizures in patients
with local lesions of the cerebral cortex.?

?It should be noted that many common antidepressants, such as
fluoxetine (Prozac), paroxetine (Paxil), and other so-called SSRIs,
can cause insomnia. Some research suggests that the newer hypnotics,
notably zolpidem (Ambien), may be useful for insomnia experienced by
people taking these agents.?

?Treatment Options for Short-Term Insomnia. Over-the-counter sleep
aids contain sedating antihistamines (eg, diphenhydramine) and should
not be used in older persons because of serious side effects and rapid
tolerance.[3] Sedating antidepressants (eg, trazodone) are used
off-label to treat insomnia. They may be helpful for patients with
comorbid depression, but there is no evidence supporting their use in
nondepressed patients.[4] The effectiveness of herbal agents (eg,
valerian and kava kava) is unclear, and these agents may potentiate
the effects of prescription hypnotics.?

?When a patient reports long-term sleep problems (lasting months to
years), the insomnia may be a primary problem or secondary to another
disorder. The diagnosis of primary insomnia (a condition in which
sleep difficulties continue in the absence of an acute stressor) is
quite rare among older adults, accounting for only 5% to 20% of
cases.[10,11] Most insomnia complaints are secondary to underlying
factors, such as medical conditions, neurologic disorders, primary
sleep disorders (described below), substance abuse, medications,
and/or psychiatric conditions.[10] Of note, there is strong evidence
that chronic insomnia has a significant impact on quality of life,
particularly for those with insomnia that is secondary to another
comorbid condition?

?Even medicines that you find on drugstore shelves can disrupt sleep.
Insomnia can be made worse by the use of caffeine or alcohol. It can
even be a result of well-intentioned behaviors such as napping. It can
also be related to depression, worry and stress. Before treating
insomnia, a doctor must first do a medical exam. He or she may also
need to perform some tests.
Doctors often treat insomnia in the three ways that follow: 

1. Sleep hygiene 
Sleep hygiene consists of basic habits and tips that help you develop
a pattern of healthy sleep. Examples include getting up at the same
time every day and avoiding caffeine after lunch.
2. Cognitive behavioral therapy 

This involves relaxation exercises and other methods that help improve
your sleep. Some people listen to relaxing tapes. Others learn
breathing exercises from a psychologist. Other methods teach you to do
things such as limiting the time you spend in bed.
3. Sleeping pills and sleeping aids 
Doctors sometimes prescribe sleeping pills to treat insomnia. These
are called hypnotics. At times insomnia is related to depression and
anxiety. In these cases, medications may be prescribed by doctors to
help insomnia.

Some people with insomnia try to treat themselves with nonprescription
sleep aids that they find on drugstore shelves. Others may try
vitamins or herbs. Some people even use alcohol to help them fall
asleep. Doing this actually makes their sleep worse. The alcohol
causes them to wake up during the night.

I urge you to visit your doctor to find a reasonable solution to your
insomnia. Good luck and Good Health!

If you find any part of this answer unclear, please request an Answer
Clarification, and allow me to respond, before you rate. I?ll be happy
to assist you further before you rate the answer.

Sincerely, Crabcakes

Search Terms
benadryl dependence
Unisom dependence
diphenhydramine  + "long term safety"
diphenhydramine  + side effects 
doxylamine succinate  + side effects + long term use
doxylamine succinate  + ?long term use?
davecraze-ga rated this answer:5 out of 5 stars

Subject: Re: Long term effects of taking common antihistamines
From: jade83081-ga on 30 Jan 2006 20:06 PST
Great answer!
Subject: Re: Long term effects of taking common antihistamines
From: jade83081-ga on 30 Jan 2006 20:08 PST
Great answer! OP, I hope you're able to get some help for your
sleeplessness. (I sometimes have problems sleeping too.)

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