Amitriptyline is a tricyclic antidepressant (TCA) that has been used for decades to treat depression and, in lower doses, other conditions like chronic nerve pain, fibromyalgia, and migraine prevention [1.5.5, 1.9.1]. It works by increasing the levels of certain natural substances in the brain, primarily serotonin and norepinephrine, which helps maintain mental balance and alter pain signals [1.5.3, 1.5.4]. While effective, its use is often accompanied by a distinct set of side effects due to its action on other receptors in the body [1.2.1].
The Most Common Side Effects of Amitriptyline
Amitriptyline's effects on histamine and acetylcholine receptors are responsible for its most frequently reported side effects [1.2.1]. Many of these are mild and may lessen as your body adjusts to the medication [1.3.4].
Frequent Anticholinergic and Antihistamine Effects
- Drowsiness and Sedation: Feeling tired or sleepy is a very common effect, which is why the medication is often taken at bedtime to aid sleep and minimize daytime drowsiness [1.2.2, 1.4.3].
- Dry Mouth (Xerostomia): A persistent feeling of dryness in the mouth is one of the most frequent complaints. This happens because the medication reduces saliva production [1.4.4, 1.2.3].
- Constipation: As a TCA, amitriptyline can slow down how fast food moves through the intestines, leading to constipation [1.4.4]. If you do not have a bowel movement for three days, you should contact your care team [1.4.1].
- Weight Gain: Increased appetite and subsequent weight gain are common [1.8.2]. Studies have shown that people taking amitriptyline may gain anywhere from one to 16 pounds [1.2.5].
- Dizziness: This often occurs due to orthostatic hypotension, which is a sudden drop in blood pressure when you stand up from a sitting or lying position [1.2.5, 1.4.3].
- Blurred Vision: The medication can affect the muscles that control the eyes' focus and can also cause dry eyes, which may be particularly uncomfortable for contact lens wearers [1.2.3, 1.4.1].
Less Common and Serious Side Effects
While less frequent, some side effects require immediate medical attention. It's crucial to be aware of these potential risks.
- Cardiovascular Effects: Amitriptyline can cause a fast or irregular heartbeat (tachycardia), palpitations, and changes in the heart's electrical activity (QTc prolongation) [1.2.1]. It should not be used by individuals with a history of certain heart conditions, such as recent myocardial infarction or arrhythmias [1.2.1].
- Urinary Retention: Some people may experience difficulty starting urination or being unable to empty their bladder completely [1.2.1, 1.3.4]. If you cannot pee at all, it requires urgent medical attention [1.3.4].
- Suicidal Thoughts and Behaviors: The FDA has issued a black box warning, its most serious type, for an increased risk of suicidal ideation, especially in children, teenagers, and young adults up to age 24 [1.5.2, 1.2.1]. Any new or worsening mood changes should be reported to a doctor immediately [1.6.1].
- Serotonin Syndrome: This is a rare but potentially life-threatening condition that can occur when medication levels become too high. Symptoms include agitation, confusion, rapid heartbeat, muscle stiffness, twitching, sweating, and fever [1.2.3].
- Seizures: Amitriptyline can lower the seizure threshold, especially at higher doses [1.2.1].
How to Manage Common Side Effects
Many of the milder side effects can be managed with simple lifestyle adjustments:
- For Drowsiness: Take the daily dose in the evening or a couple of hours before bed [1.9.2]. Avoid driving or operating heavy machinery until you know how the medication affects you [1.4.5].
- For Dry Mouth: Sip water regularly, chew sugar-free gum, or suck on sugar-free hard candies to stimulate saliva flow [1.4.1, 1.4.3].
- For Constipation: Increase your intake of high-fiber foods like fruits, vegetables, and cereals, drink plenty of water, and get regular exercise [1.4.3].
- For Dizziness: Get up slowly from a sitting or lying position to allow your blood pressure to adjust [1.4.1].
- For Sun Sensitivity: Amitriptyline can make your skin more sensitive to the sun. Wear protective clothing, use sunscreen with a high SPF, and avoid sunlamps or tanning beds [1.4.1].
Comparison Table: Amitriptyline vs. Other Antidepressants
Amitriptyline's side effect profile is a key reason why newer classes of antidepressants, like SSRIs, are often prescribed first [1.7.3].
| Feature | Amitriptyline (TCA) | Fluoxetine (SSRI) | Venlafaxine (SNRI) |
|---|---|---|---|
| Mechanism | Increases serotonin and norepinephrine [1.5.3] | Primarily increases serotonin | Increases serotonin and norepinephrine |
| Common Side Effects | Drowsiness, dry mouth, constipation, weight gain, dizziness [1.8.4] | Nausea, insomnia, headache, sexual dysfunction [1.7.3] | Nausea, dizziness, sweating, sexual dysfunction, potential for increased blood pressure |
| Key Advantages | Effective for nerve pain and migraine prevention; sedative properties can aid sleep [1.9.1] | Generally better tolerated with fewer anticholinergic effects [1.7.3] | Can be effective for depression and anxiety; also used for nerve pain |
| Key Disadvantages | Higher burden of side effects (anticholinergic, cardiac risks); more dangerous in overdose [1.2.1, 1.11.4] | Can cause agitation or anxiety initially; withdrawal symptoms are possible | Withdrawal symptoms can be severe if stopped abruptly; blood pressure monitoring needed |
When to Contact a Healthcare Provider
You should contact your doctor immediately if you experience any of the following:
- Thoughts of suicide or self-harm [1.3.2].
- Fast or irregular heartbeat, chest pain, or feeling faint [1.3.2, 1.3.4].
- Signs of a stroke, such as weakness on one side of the body or trouble speaking [1.3.4].
- Signs of a liver problem, like yellowing of the skin or eyes (jaundice) [1.3.4].
- Severe allergic reactions, including swelling of the face, tongue, or throat, and difficulty breathing [1.3.2].
- Sudden eye pain or significant changes in vision [1.3.2].
Conclusion
Amitriptyline remains a useful medication for depression, chronic pain, and other conditions. However, its effectiveness must be weighed against its potential side effects. The most common effects, such as drowsiness and dry mouth, are often manageable and may decrease over time [1.3.4]. More serious risks, particularly cardiac effects and the potential for increased suicidal thoughts in young people, require careful monitoring by a healthcare professional [1.2.1]. Open communication with your doctor about any side effects you experience is essential to ensure the medication is both safe and effective for you. Do not stop taking amitriptyline suddenly without medical advice, as this can cause withdrawal symptoms [1.5.2].
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional before starting or stopping any medication. For official patient information, you can review resources from the NHS.
