Amitriptyline dosage, forms, and strengths

Amitriptyline (originally sold as Elavil) is a generic prescription antidepressant that relieves the symptoms of depression. Healthcare providers also prescribe it off-label to treat anxiety, insomnia, post-traumatic stress disorder (PTSD), irritable bowel syndrome (IBS), nerve pain due to herpes infection (postherpetic neuralgia), and chronic pain due to fibromyalgia or diabetic nerve damage. It’s also commonly used to prevent migraines. Amitriptyline belongs to the first generation of antidepressants called tricyclic antidepressants (TCAs). These drugs slow down the reuptake of certain chemicals in the brain called serotonin and norepinephrine. With increased levels of these neurotransmitters in the brain, people can better regulate their mood. Common side effects include drowsiness, dizziness, dry mouth, blurred vision, and weight gain. Because amitriptyline commonly causes drowsiness, doses are usually taken at night before bedtime.

Amitriptyline forms and strengths

Amitriptyline is only available as tablets, but a compounding pharmacy can prepare an oral solution for people who can’t swallow tablets. 

• Tablets: 10 milligrams (mg), 25 mg, 50 mg, 75 mg, 100 mg, 150 mg

Amitriptyline dosage for adults

The FDA- has approved amitriptyline only for treating depression. Healthcare providers often prescribe amitriptyline for off-label conditions such as insomnia and migraine prevention. 

Amitriptyline dosage for depression

Amitriptyline is FDA-approved to treat depression. Most other antidepressants, including SSRIs, are only approved to treat major depressive disorder (MDS), a clinical diagnosis that includes five or more depression symptoms that last longer than two weeks. For amitriptyline, the clinician has more leeway to treat depressive symptoms that don’t meet the diagnostic criteria for MDS. This includes exogenous depression or depression due to an outside event, such as losing a loved one. Because there are more effective medications to treat depression, amitryptiline is rarely used to treat depression.

• Standard adult dosage for depression: 50–150 mg daily taken in divided doses or a single dose at bedtime

Amitriptyline dosage for sleep

Drowsiness is a common side effect of amitriptyline so clinicians often have patients take it before bed. This sedative side effect helps people fall asleep and is particularly helpful in people with long-term insomnia or who have both insomnia and depression. Amitriptyline is not always a first choice because it may affect sleep quality.

• Standard adult dosage for insomnia: 10–50 mg daily by mouth taken at bedtime

Amitriptyline dosage for migraine

Amitriptyline is a second-line treatment to prevent migraines. It is highly effective, but healthcare professionals don’t know why. Because of its sedative effects, healthcare providers typically advise that the tablet be taken at night before bedtime. 

• Standard adult dosage for migraine prophylaxis: 10–75 mg daily taken by mouth at bedtime

Amitriptyline dosage for children

Amitriptyline is not FDA-approved as safe or effective in children younger than 12 due to limited safety and efficacy data available. Some healthcare providers prescribe amitriptyline off-label for nerve pain or migraine prevention in children as young as two. 

For adolescents, healthcare providers often use lower doses than prescribed to adults, though these reduced doses are not specified. As with other antidepressants, amitriptyline increases the risk of suicidal thoughts and behaviors in children, adolescents, and young adults. Both healthcare professionals and caregivers should carefully monitor a teen taking amitriptyline for signs of worsening depression or suicidality. If patients have thoughts of harming themselves or others they should seek emergent care or call 911 to keep them safe until the thoughts subside.

Amitriptyline dosage restrictions

Amitriptyline has no dosage adjustment needed for people with liver disease or reduced kidney function. However, the Food and Drug Administration (FDA) recommends low doses in older adults. The suggested dosage is 10 mg daily or 20 mg at bedtime.

Amitriptyline dosage for pets 

Veterinarians use amitriptyline in dogs and cats for anxiety or anxiety-related behaviors. For dogs, veterinarians use amitriptyline to treat anxiety-related aggression, separation anxiety, submission urination, and as an add-on drug for itching caused by allergies. The latter may seem oddly out of place, but amitriptyline also has antihistamine effects. For cats, vet professionals use amitriptyline for marking problems or excessive screaming and meowing that are not pain-related. Veterinarians are likely to give pet owners a liquid form of amitriptyline to measure out and give doses more accurately.

• Standard amitriptyline dosage for dogs: 1-2 mg/kg daily

• Standard amitriptyline dosage for cats: 0.5-1 mg/kg daily

How to take amitriptyline

Taking amitriptyline is relatively straightforward. Most people take their dose at night before bedtime. If swallowing a tablet is impossible, ask the prescribing healthcare provider about getting an oral solution from a compounding pharmacy. 

• Take your medicine as directed. Your dose may need to be changed to find the most effective dose.

• The clinician may prescribe this medicine to be taken before bedtime.

• Take a missed dose as soon as it’s remembered. If it’s almost time for the next dose, skip the missed dose and take the next dose as scheduled. Do not take extra medicine to make up for a missed dose.

• Read the medication guide that comes with the medicine. If there is no medication guide, ask the pharmacist for one.

• Do not stop taking this medicine until talking to the prescriber or other healthcare provider. 

• Store the medicine in a closed container at room temperature, away from heat and direct light.

Amitriptyline dosage FAQs

How long does it take amitriptyline to work?

Many people will notice improvement in their depression symptoms within one or two weeks of starting amitriptyline. They will continue to feel better until the full effects are felt four to six weeks after daily use. 

How long does amitriptyline stay in your system?

The beneficial and adverse effects of amitriptyline can last for several days. The body breaks down amitriptyline into a similar drug called nortriptyline, also prescribed to treat depression. Nortriptyline has the same effects as amitriptyline and is about as strong. The half-life of amitriptyline is 10 to 26 hours. The half-life of nortriptyline is 18 to 44 hours. It could take a week or more for amitriptyline and its active metabolite to fall to undetectable levels after the medication is stopped. 

What happens if I miss a dose of amitriptyline?

Take a missed dose as soon as it’s remembered unless it’s almost time for the next dose. In that case, skip the missed dose and take the next dose as scheduled. Remember that amitriptyline should be taken at bedtime because of its sedative effects. If you take a missed dose the next morning, common side effects of drowsiness and dizziness may significantly interfere with your ability to function. Do not drive a car or engage in risky activity if a dose of amitriptyline is causing impairment.

How long can you take amitriptyline?

Amitriptyline is intended for long-term, but not lifetime, treatment. Healthcare providers typically prescribe amitriptyline until depressive symptoms have been adequately controlled for at least three months. It may be used longer for off-label uses as long as it works and the side effects are manageable. 

How do I stop taking amitriptyline?

Do not stop taking amitriptyline without talking to the prescribing clinician or other healthcare professionals. Sudden amitryptiline discontinuation can cause withdrawal symptoms, most commonly worsening the condition being treated. The prescriber may reduce the dose gradually when stopping treatment.

What is the maximum dosage for amitriptyline?

In the FDA drug information, the maximum specified amitriptyline dosage is 300 mg daily for depression in hospitalized patients. No maximum dosages have been determined for off-label uses, though the dosages generally are lower than those for depression.

Can you overdose on amitriptyline?

Yes. An overdose of amitriptyline can cause serious or even life-threatening complications, especially when combined with alcohol or other central nervous system depressants. Symptoms of an amitryptiline overdose includes irregular heartbeats, racing heartbeats, very low blood pressure (hypotension), excessive sedation, confusion, inability to concentrate, hallucinations, vomiting, hypothermia, high fever, convulsions, or coma. If too much amitriptyline is suspected, call a poison control center or get immediate emergency medical care. 

What interacts with amitriptyline?

Like other antidepressants, amitriptyline can have unpleasant or even serious drug interactions. Tell the prescribing clinician and pharmacist about other medications or supplements being taken.

At the top of the drug interactions list are monoamine oxidase inhibitors or MAO inhibitors (MAOIs). These are absolutely contraindicated for use with amitriptyline, so they must be discontinued at least 14 days before amitriptyline can be safely taken. MAO inhibitors are rarely prescribed. Other contraindicated drugs include the GERD medication cisapride and the antipsychotic drugs pimozide and thioridazine because of the increased risk of irregular heartbeats (arrhythmias).

Other drug combinations may cause problems by increasing the risk of common or worsening serious side effects of amitriptyline. These include:

• Central nervous system depressants such as opioids, sedatives, benzodiazepines, and muscle relaxants increase the risk of excessive sedation when combined with amitriptyline

• Drugs that affect serotonin levels increase the risk of serotonin syndrome in combination with amitriptyline—the most serious include other antidepressants such as sertraline, paroxetine, or fluoxetine, anti-anxiety medications, antipsychotics, anticonvulsants, and migraine medications called triptans

• Anticholinergic drugs like bronchodilators or the bladder control drug oxybutynin may worsen some of the anticholinergic side effects of amitriptyline such as dry mouth, constipation, urinary retention, fever, racing heart rate, and neurological problems.

What happens when you mix amitriptyline and alcohol?

Avoid drinking alcohol on days amitriptyline is taken. Combining alcohol with amitriptyline amplifies the sedative effects of both substances.

Is it safe to take amitriptyline during pregnancy?

Healthcare professionals aren’t certain about the safety of amitriptyline treatment during pregnancy. There are too few studies to help guide the decision. Amitriptyline does cross the placenta, and problems in the baby’s development have been reported. In addition, there is also evidence that amitriptyline may cause complications of high blood pressure in pregnant women. Women considering pregnancy or currently pregnant should ask the prescribing clinician for medical advice about the risks and benefits. 

Is it safe to take amitriptyline while breastfeeding?

Healthcare professionals prescribe amitriptyline to breastfeeding mothers. Low levels of amitriptyline are found in human breast milk, but studies have shown no detectable amitriptyline levels in nursing babies. No studies have shown any adverse effects in nursing infants. The World Health Organization considers amityrptiline to be compatible with breastfeeding when the mother takes 150 mg a day or less. 

Related resources for amitriptyline dosages:

• Amitriptyline, StatPearls

• Amitriptyline for dogs, SingleCare

• Amitriptyline for sleep, SingleCare

• Amitriptyline hydrochloride tablet prescribing information, National Library of Medicine

• Is it safe to take amitriptyline during pregnancy?, SingleCare