Medicines that can change your dreams

This article is for information only. It is not advice about any particular medicine. Never stop or change a medicine on your own; talk to your doctor or pharmacist.

Sometimes nightmares arrive with no obvious reason, and then you notice the timing: a new prescription, a changed dose, a tablet you stopped last week. Medicines really can change dreams. Knowing that can take some of the fear out of it, and give you something useful to discuss with the person who prescribes for you.

Why a medicine can reach your dreams

Dreaming depends on brain chemistry. A 2003 review of case reports and clinical trials found that medicines affecting three chemical messengers, noradrenaline, serotonin and dopamine, are clearly associated with reports of nightmares. It found a possible link for medicines acting on acetylcholine, GABA and histamine, and for some anaesthetics, antipsychotics and anti-epileptic medicines. Medicines that affect the immune response to infection were also likely to cause nightmares in some people.^[1]

Timing matters too. Many medicines reduce REM sleep, the stage in which the most vivid dreams happen. When such a medicine is stopped, REM can rebound for a while, and dreams may become more intense or frightening.^{[3, 4]} Alcohol does something similar over a single night, which we cover in alcohol, cannabis and the second half of the night.

How good is the evidence?

Mostly modest. Much of it comes from case reports and from side-effect lists in clinical trials. A 1999 review pointed out the central problem: nightmares are common in healthy people anyway, so it is hard to be sure a medicine caused them. Using the evidence available, it concluded that sedatives and sleep medicines, beta blockers and amphetamines were the medicines most often associated with nightmares, with dopamine agonists also showing evidence of a link.^[2]

So a link in the literature does not mean a medicine will change your dreams, and many people take these medicines without any change in their dreams.

Groups of medicines often reported

A little more on each, with the sources:

• Beta blockers. They act on the noradrenaline system, which gives a plausible route to dreams, and they appear repeatedly in reviews of medicine-related nightmares.^{[1, 2]}
• Antidepressants. A systematic review found that almost all antidepressants reduce REM sleep, and the main finding was fewer remembered dreams. Taking some newer antidepressants, and even more so stopping them, seems to intensify dreaming, and stopping some older antidepressants may cause nightmares.^[3]
• Varenicline. In the trials behind its US approval, abnormal dreams (described as vivid, unusual or strange) were among the most common side effects, reported by about 13 in 100 people on the standard dose compared with 5 in 100 on placebo.^[5]
• Sleep medicines. Sedatives and sleep medicines are among the groups most often associated with nightmares, and stopping medicines that suppress REM sleep can bring nightmares as REM rebounds.^{[2, 4]}
• Acetylcholinesterase inhibitors. These raise acetylcholine, a messenger involved in REM sleep. In pooled trials of donepezil in mild to moderate Alzheimer’s disease, abnormal dreams were reported by 3 in 100 people, compared with none on placebo.^{[1, 6]}

Stopping can change dreams too

Because REM sleep can rebound when some medicines are withdrawn, the weeks after stopping can bring stranger or stronger dreams than the weeks on the medicine.^{[3, 4]} This is one more reason never to stop a medicine abruptly on your own. Some medicines need to be reduced slowly with medical guidance, and stopping can also bring back the condition they were treating.

What helps if your dreams change

1. Notice the timing. Did the change begin after a new medicine, a different dose, or stopping something?
2. Keep a short note for a week or two. How vivid or distressing the dreams were, how you slept, and anything else that might matter, such as alcohol, illness or stress.
3. Talk to your doctor or pharmacist. You might ask whether this is a known effect, whether it is likely to settle, and what the options are. Keep taking the medicine as prescribed unless they advise otherwise.
4. Ask for help sooner if a new medicine comes with low mood, agitation or thoughts of harming yourself. Contact your doctor straight away, call your local emergency number, or reach out to a crisis line.

If nightmares keep returning after the medicine question has been sorted out, there are well-established ways to work with them, such as imagery rehearsal.

Baku’s moon calendar of nights can make a pattern like this easier to see, and easier to describe when you talk to your doctor.