Question

Although taking a low dose amitriptyline has been very useful in reducing some of my pain and helping to correct my very erratic sleep pattern (frequent wakening during the night) I’ve put on a considerable amount of weight since taking this drug. My GP says that weight gain is a well recognised side-effect with this type of drug and that it can also occur with other drugs that are used for pain relief. I know from talking to other people with ME that weight gain can be a major problem with some drug treatments for ME. But why is this so? And are there any solutions?

Answer

Unfortunately, weight gain is a potential side-effect with most types of antidepressant drugs. However, everyone responds to antidepressants differently. While some people gain weight when taking a certain type of antidepressant, others do not. Generally speaking, certain antidepressants seem more likely to cause weight gain than others. These include:

• Older types of tricyclic antidepressants such as amitriptyline, imipramine (Tofranil) and doxepin.
• Paroxetine (Paxil), a selective serotonin reuptake inhibitor (SSRI).
• Mirtazapine, an atypical antidepressant drug that doesn’t fit neatly into any current antidepressant category.

Some people gain weight after starting an antidepressant, especially when used at higher doses to treat depression compared to the much lower doses that are used for pain or sleep disturbance. But the antidepressant isn’t always a direct cause. Other factors can also contribute to weight gain during antidepressant therapy where the drug is being used to treat depression. For example:

• Overeating or inactivity as a result of depression will cause weight gain. Some people lose weight as part of their depression. So an improved appetite associated with improved mood during treatment may result in increased weight.
• Adults generally tend to gain weight as they age, regardless of the medications they take. If you gain weight after starting an antidepressant for whatever reason, weigh up the benefits and side-effects and talk to your GP. If the benefits outweigh the side-effect of weight gain, consider managing your weight by making some dietary changes.
• Other drugs that can also cause weight gain include antihistamines such as cetirizine, beta blockers and gabapentin (Neurontin).

You can also check with your GP to see if adjusting the dose or switching to another drug might be helpful.

WebMD: 

Are Your Meds Making You Gain Weight? | April 2015

See also: 

• • The 2021 NICE Guideline ME/CFS: Drug Treatments.
  • Treatments: Drug Sensitivities and Side Effects.
  • Treatments: Prescribed Drugs and Informed Consent.

More information

The ME Association has several detailed leaflets that include information about symptom-relieving medications such as SSRIs:

• We explain depression and how it is completely understandable when living with ME/CFS. We also review treatment options including SSRIs and antidepressants, self-help, good CBT, and, counselling.
  • Visit the Mental Health section to review all the information we have available on this topic.
    • We explain how Amitriptyline was developed as an antidepressant, but is now used more commonly to help with pain and sleep problems that occur in ME/CFS.
    • We discuss anxiety, depression and pain in ME/CFS, and feature the drug Duloxetine and review the evidence for its use as a symptom-relieving medication.
• We talk about pain in ME/CFS and feature Lyrica, reviewing the evidence for its use as a pain relief medication, and its legal status as a Class C controlled Drug.
• We talk about pain in ME/CFS and feature Gabapentin, review the evidence for its use as a pain relief medication, and its legal status as a Class C controlled Drug.