Serotonin syndrome

[David Baxter PhD]

Serotonin syndrome
By Mayo Clinic Staff
Feb. 7, 2009

Serotonin syndrome occurs when you take medications that cause high levels of the chemical serotonin to accumulate in your body. It can occur when you increase the dose of such a drug or add a new drug to the ones you take already. Certain illicit drugs and dietary supplements also can cause serotonin syndrome.

Serotonin is a chemical produced by your body and is needed for your nerve cells and brain to function. But too much serotonin causes problems. Symptoms of serotonin syndrome range from shivering and diarrhea to severe symptoms such as muscle rigidity, fever and seizures. Severe serotonin syndrome can be fatal if it isn't treated. Serotonin syndrome usually goes away within a day of stopping the medications causing symptoms and taking drugs that block serotonin, if needed.

Symptoms
Serotonin syndrome symptoms typically occur within several hours of taking a new drug or increasing the dose of a drug you're already taking. Signs and symptoms include:

• Agitation or restlessness
• Confusion
• Rapid heart rate
• Dilated pupils
• Loss of muscle coordination or twitching muscles
• Heavy sweating
• Diarrhea
• Headache
• Shivering
• Goose bumps

Severe serotonin syndrome can be life-threatening. Signs and symptoms include:

• High fever
• Seizures
• Irregular heartbeat
• Unconsciousness

When to see a doctor
If you suspect you might have serotonin syndrome after starting a new drug or increasing the dose of a drug you're already taking, call your doctor right away or go to the emergency room. If you have severe or rapidly worsening symptoms, seek emergency treatment immediately.

Causes
Nerve cells in your brain and spinal cord (central nervous system) produce serotonin that helps regulate your attention, behavior and body temperature. Other nerve cells in your body, primarily in your intestines, also produce serotonin. In these other areas, serotonin plays a role in regulating your digestive process, blood flow and breathing. Too much serotonin can cause serotonin syndrome.

In some cases, serotonin syndrome can be caused by taking just one drug that increases serotonin levels, but it occurs most often when you combine certain medications. For example, serotonin syndrome may occur if you take an antidepressant along with a migraine medication. A common cause of serotonin syndrome is intentional overdose of antidepressant medications.

A number of over-the-counter and prescription drugs can lead to serotonin syndrome, especially antidepressants. Illicit drugs and dietary supplements also can cause the condition. These drugs and supplements include but aren't limited to:

• Serotonin reuptake inhibitors (SSRIs), antidepressants such as citalopram (Celexa), fluoxetine (Prozac, Sarafem), fluvoxamine, paroxetine (Paxil) and sertraline (Zoloft)
• Serotonin and norepinephrine reuptake inhibitors (SNRIs), antidepressants such as trazodone and venlafaxine (Effexor)
• Bupropion, an antidepressant and tobacco-addiction medication (Wellbutrin, Zyban)
• Monoamine oxidase inhibitors (MAOIs), antidepressants such as isocarboxazid (Marplan) and phenelzine (Nardil)
• Anti-migraine medications such as almotriptan (Axert), naratriptan (Amerge), sumatriptan (Imitrex) and zolmitriptan (Zomig)
• Pain medications such as fentanyl (Sublimaze), meperidine (Demerol), pentazocine, (Talwin) and tramadol (Ultram)
• Lithium (Eskalith, Lithobid), a mood stabilizer
• Illicit drugs, including LSD, Ecstasy, cocaine and amphetamines
• Herbal supplements, including St. John's wort and ginseng
• Over-the-counter cough and cold medications containing dextromethorphan (Robitussin DM, Sudal DM)
• Anti-nausea medications such as granisetron (Kytril), metoclopramide (Reglan) and ondansetron (Zofran)
• Linezolid (Zyvox), an antibiotic
• Ritonavir (Norvir), an anti-retroviral medication used to treat HIV/AIDS

Risk factors
Some people are more susceptible to the drugs and supplements that cause serotonin syndrome than are others, but the condition can occur in anyone.

You're at increased risk of serotonin syndrome if:

• You recently started taking or increased the dose of a new medication known to increase serotonin levels
• You take more than one drug known to increase serotonin levels
• You take herbal supplements known to increase serotonin levels
• You use an illicit drug known to increase serotonin levels

Complications
Serotonin syndrome generally doesn't cause any problems once serotonin levels are back to normal. But if left untreated, severe serotonin syndrome can lead to unconsciousness and death.

Preparing for your appointment
Because serotonin syndrome can be a life-threatening condition, seek emergency treatment right away if you have worsening or severe symptoms.

If your symptoms aren't severe, you're likely to start by first seeing your family doctor or a general practitioner. Because appointments can be brief, and because there's often a lot of ground to cover, it's a good idea to be well prepared for your appointment. Here's some information to help you get ready for your appointment, and what to expect from your doctor.

What you can do

• Be aware of any pre-appointment steps you need to take. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as quitting any of the current medications or supplements you take.
• Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
• Write down key personal information, including any major stresses or recent life changes.
• Make a list of all medications, as well as any vitamins or supplements that you're taking.
• Take a family member or friend along, if possible. Sometimes it can be difficult to soak up all the information provided to you during an appointment. Someone who accompanies you may remember something that you missed or forgot.
• Write down questions to ask your doctor.

Your time with your doctor is limited, so preparing a list of questions will help you make the most of your time together. List your questions from most important to least important in case time runs out. For symptoms you think may be caused by serotonin syndrome, some basic questions to ask your doctor include:

• Is serotonin syndrome most likely causing my symptoms, or could it be something else?
• Other than the most likely cause, what are other possible causes of my symptoms?
• What kinds of tests do I need?
• What is the best course of action?
• What are the alternatives to the primary approach that you're suggesting?
• I have these other health conditions. How can I best manage them together?
• Can I still take the medications I've been prescribed, or will I need to change them or change the dose?
• Are there any restrictions that I need to follow, such as avoiding certain drugs or supplements?

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.

What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over any points you want to spend more time on. Your doctor may ask:

• When did you first begin experiencing symptoms?
• Have your symptoms been continuous, or occasional?
• How severe are your symptoms?
• What prescription and over-the-counter medications do you take?
• Do you use any illicit drugs?
• Do you take any dietary supplements?

Tests and diagnosis
No single test can confirm a serotonin syndrome diagnosis. Your doctor will diagnose the condition by ruling out other possibilities.

Your doctor will likely begin by asking about your medical history and any medications you're taking. To make sure your symptoms are caused by serotonin syndrome and not something else, your doctor may use tests to:

• Measure levels of any drugs you're using
• Check your thyroid hormone level
• Check body functions that may be affected by serotonin syndrome

A number of conditions can cause symptoms similar to those caused by serotonin syndrome. Minor symptoms can be caused by numerous conditions. Causes of moderate and severe symptoms include:

• Anticholinergic syndrome, malignant hyperthermia and neuroleptic malignant syndrome, serious conditions caused by certain medications
• An overdose of cocaine, amphetamines or an MAOI, a type of drug for depression
• Certain thyroid conditions
• Withdrawal from alcohol or heroin

Treatments and drugs
Treatment of serotonin syndrome depends on the severity of your symptoms.

• If your symptoms are minor, a visit to the doctor and stopping the medication causing the problem may be enough.
• If you have symptoms that concern your doctor, you may need to go to the hospital. Your doctor may have you stay in the hospital for several hours to make sure you're OK.
• If you have severe serotonin syndrome, you may need additional medications and longer hospitalization.

Depending on your symptoms, you may receive the following treatments:

• Muscle relaxants. Benzodiazepines, such as diazepam (Valium) or lorazepam (Ativan), can help control agitation, seizures and muscle stiffness.
• Serotonin-production blocking agents. If other treatments aren't working, medications such as cyproheptadine can help by blocking serotonin production.
• Oxygen and intravenous (IV) fluids. Breathing oxygen through a mask helps maintain normal oxygen levels in your blood, and IV fluids are used to treat dehydration and fever.
• Drugs that control heart rate and blood pressure. These may include esmolol (Brevibloc) or nitroprusside (Nitropress), to reduce a high heart rate or high blood pressure. If your blood pressure is too low, your doctor may give you phenylephrine (Neo-Synephrine) or epinephrine.
• A breathing tube and machine and medication to paralyze your muscles. These may be necessary if you have a high fever.

Serotonin syndrome symptoms usually go away within 24 hours of stopping medications that increase serotonin, and taking medications to block the effects of serotonin already in your system if they're needed. However, symptoms of serotonin syndrome caused by some antidepressants could take several weeks to go away completely. These medications remain in your system longer than other medications that can cause serotonin syndrome.

Prevention
Taking more than one serotonin-related medication may increase your risk of serotonin syndrome. This can be especially true if you're taking a serotonin reuptake inhibitor or a serotonin and norepinephrine reuptake inhibitor. Talk to your doctor about possible risks. Don't stop taking any such medications on your own. If your doctor prescribes a new medication, make sure he or she knows about all the other medications you're taking ? especially if you receive prescriptions from more than one doctor.

If you and your doctor decide the benefits of combining certain serotonin-level-affecting drugs outweigh the risks, be alert to the possibility of serotonin syndrome.

 

[ladylore]

Herbal supplements, including St. John's wort and ginseng

That is a bit scary - I don't take these any longer but I did for many, many years. I didn't know they could be a cause of Serotonin syndrome.

 

[David Baxter PhD]

That is a bit scary - I don't take these any longer but I did for many, many years. I didn't know they could be a cause of Serotonin syndrome.

Unfortunately, a lot of people aren't aware of the dangers of herbal and "natural" medications.

Among several other things, many women don't realize that St. John's Wort reduces the effectiveness of birth control pills.

 

[Retired]

St. John's Wort reduces the effectiveness of birth control pills

Certain antibiotics, minor tranquilizers (benzodiazepines) and anti depressants (SSRI's) can reduce the effectiveness of low dose oral contraceptives.

Whenever a new prescription is received, the prescriber should be given a list of all prescription and over the counter, inlcuding herbal preparations being taken so drug interactions can be avoided.

The pharmacist should also be questioned, in case something may have been missed by the prescriber, and finally using a reliable online interaction checker can be useful.