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Q: prescription drug interactions ( Answered 4 out of 5 stars,   5 Comments )
Subject: prescription drug interactions
Category: Health
Asked by: betsyj-ga
List Price: $25.00
Posted: 21 Jul 2005 11:07 PDT
Expires: 20 Aug 2005 11:07 PDT
Question ID: 546278
What would be the most likely side effects/interactions, if any, 
for a person taking the following medications:  Effexor XR (300mg/day),
Lorazepam (.5mg/day), Levoxyl (.088mg/day), and Ortho Tri-cyclen 28
(birth control pill)?
Subject: Re: prescription drug interactions
Answered By: raisingmyhand-ga on 26 Jul 2005 03:52 PDT
Rated:4 out of 5 stars
Dear Betsyj, hello and thanks for a great medical question. 

To answer your question, I used a medical software program called
Epocrates Rx Pro (, which is
designed to help health professionals look up information on
medications, including side effects/adverse reactions and potential
interactions between medications for patients who are on, or being
considered for, multiple medicines. This program is widely used and
highly respected, for example, it is used by pharmacists at Provena
Saint Joseph Hospital, Elgin,
and is even mentioned on the FDA web site as a way to reduce adverse
drug reactions (though the product is not officially endorsed by the

I first checked to see if there were any expected interactions between
the medicines and then looked at the adverse reactions (side effects)
for each one.

To evaluate for any possible interactions, I used the function called
"multi-check", and entered the names of the medicines you listed in
your question. No advisories to alter or monitor the combination were
given but instead I retrieved the following summary statement:

"No interactions found for drugs selected. Caution always advised with
multiple medications."

This is an excellent and fully up-to-date software program that
represents the current knowledge in modern western medicine. Thus, I
feel fairly confident in telling you that there are no likely
interactions for the medicines that you listed. The interpretation is
that as far as is known, there is no significant interaction between
any of the medications that you listed. In other words, a physician
prescribing this combination could focus on possible adverse from any
one medication on the list, but need not worry about interactions.

Almost all medicines have possible side effects and the ones you
listed are no exception. I looked up each one on the Epocrates program
and have listed the results for you here. They are listed in groups by
"serious reactions" and by "common reactions." The Common Reactions
are listed in order of their relative frequency, with more common
reactions being listed first.

a) Effexor XR (venlafaxine)
SERIOUS REACTIONS: seizures, suicidality, worsening depression,
withdrawal symptoms, anaphylaxis, mania, hypertension, hyponatremia,
SIADH (syndrome of inappropriate ADH), serotonin syndrome,
extrapyramidal symptoms, abnormal bleeding, blood dyscrasias,
arrhythmias, severe skin reactions, glaucoma, pancreatitis.

COMMON REACTIONS: nausea, headache, somnolence, dry mouth, dizziness,
insomnia, constipation, nervousness, sweating, asthenia, abnormal
ejaculation, anorexia, diarrhea, blurred vision, vomiting, anxiety,
impotence, infection, hypercholesterolemia, tremor, dyspepsia,
vasodilation, abnormal dreams, yawning, paresthesias, rash,
hypertension, tachycardia, chills.

b)Lorazepam (generic)
SERIOUS REACTIONS: Cardiovascular collapse, respiratory depression,
withdrawal syndrome, gangrene (if intra-arterial), blood dyscrasias,

COMMON REACTIONS: sedation, dizziness, weakness, ataxia, depression,
nausea, antegrade amnesia, headache, sleep disturbance, agitation,
rhythmic myoclonic jerks, urinary incontinece, diplopia, nystagmus.

c)Ortho Tri-Cyclen
SERIOUS REACTIONS: thromboembolism, retinal thrombosis,
thrombophlebitis, myocardial infarction, cerebral thrombosis, cerebral
hemorrhage, severe hypertension, hepatic adenoma, cholestatic
jaundice, gallbladder disease, depression, anaphylaxis/anaphylactoid

COMMON REACTIONS: Nausea/vomiting, abdominal cramps, bloating,
breakthrough bleeding, altered menstrual flow, amenorrhea, breast
tenderness, breast changes, edema, headache/migraine, weight changes,
cervical secreation changes, emotional lability, vaginal candidiasis,
rash, acne, melasma, contact lens intolerance, elevated BP, glucose

I hope that this information is helpful to you. If you have other
specific questions about medications and possible side effects we look
forward to your posting them. Let me know if I can clarify any of this
for you.

Take care and best of luck, 

Search strategy: Epocrates Rx Pro Multicheck and Adverse Reactions
available for handheld at
betsyj-ga rated this answer:4 out of 5 stars and gave an additional tip of: $10.00

Subject: Re: prescription drug interactions
From: scubajim-ga on 21 Jul 2005 11:11 PDT
It is best to ask your DR or pharmasist.  Sometimes it depends upon
the brand etc. (sometimes "inert" parts of the medication can
interact) Your pharmasist or Dr. needs to look up the NDC numbers and
determine the interaction.
Subject: Re: prescription drug interactions
From: bkdaniels-ga on 21 Jul 2005 19:28 PDT
Hey betsyj-ga, how are you doing?

Although the cause of this potential interaction is not clearly
understood, when taken together, oral contraceptives may increase the
effects of lorazepam. Patients taking these medications together
should be monitored for side effects of lorazepam such as drowsiness,
dizziness, and impaired motor functioning (impaired muscle control)
and may need the dose of lorazepam reduced.

Intolerable or otherwise undesirable side effects may occur when
lorazepam is taken with alcoholic beverages or alcohol-containing
products (such as some cough syrups and elixirs). Potential side
effects include drowsiness, dizziness, blurred vision, headache, and

When oral contraceptives are taken with alcoholic beverages or
alcohol-containing products (such as some cough syrups and elixirs),
blood levels of alcohol could be increased. Because the combination of
oral contraceptives and alcohol (ethanol) may impair your judgment
and/or reflexes, it may be dangerous to drive or to perform tasks
which require you to be alert after taking these together.

NOTE: Not all drug interactions are known or reported in the
literature, and new drug interactions are continually being reported.
You may want to ask your healthcare provider about this potential
interaction if you think you are having problems.

Express Scripts ( Check Interactions

Best wishes,
Subject: Re: prescription drug interactions
From: willcc-ga on 21 Jul 2005 20:18 PDT
I'm not an official Google Answerer, but one of the comments stated that: 
"when taken together, oral contraceptives may increase the
effects of lorazepam."

However, oral contraceptives may increase the metabolism of
benzodiazepines, which includes lorazepam.  The reason for this is
that the estrogen in oral contraceptives increases the rate of
glucuronidation of the benzodiazepines, thereby increasing the
clearance of the drug from the body.  This decreases blood levels, so
your dose of lorazepam would probably need to be increased (not

If you were already taking the oral contraceptives before starting the
other medications, then your dose is probably already correct.
Subject: Re: prescription drug interactions
From: consulting-ga on 02 Aug 2005 03:14 PDT
Hi Betsyj,

Just to add a couple of extra resources that you can use yourself to
check side effects of medications:

-- A company called Cerner Multum produces one of the leading drug
information databases ( Although it's database
isn't available directly from the company in a web-accessible form,
some or all of it is available from third party websites like (

-- The Merck Manual is also available free on the web, directly from
Merck, and contains a wealth of medical and drug information

-- The British National Formulary, the most widely used prescription
drug reference in the United Kingdom, is also now available online for
free ( If you are in the United States, be sure to
take note of possibly differing dosages and occasionally different
spellings (e.g., Efexor vs. Effexor).

-- Simple summarized information about drugs commonly used in mental
health (e.g., Effexor, Lorazepam) is available from
( Each page of
medication information at that site also includes a link to the
original FDA-approved product insert for the drug.

At the end of the day, there's no substitute for direct advice and
consultation with your own primary care physician. But for times when
you'd just like to find some additional information on your own, I
hope these might help!
Subject: Re: prescription drug interactions
From: wiwjorra-ga on 29 Aug 2005 11:33 PDT
When I quit EFEXOR XR (cold turkey) 150mg per day, I had a buzzing in
my head for about three weeks.

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