Medications that cause dry mouth, and why it's often worse at night

Medications are one of the most common reasons for a dry mouth. The American Dental Association (ADA) says the most frequent cause of reduced saliva is the use of certain medications, and Cleveland Clinic says hundreds of prescription and over-the-counter medicines can reduce how much saliva your body makes. If your mouth feels driest at night or first thing in the morning, the timing has a simple explanation too, which we cover below.

This article walks through the main drug classes, why they dry the mouth, and what to ask your doctor or pharmacist. It isn't medical advice, and the most important rule comes first: don't stop or change a prescribed medicine on your own.

Which medications cause dry mouth?

Medications that cause dry mouth span many classes, with antihistamines, antidepressants, blood pressure medicines, diuretics, bladder medicines and opioid painkillers among the most common. A 2017 systematic review sponsored by the World Workshop on Oral Medicine screened 3,867 records and found 56 drugs with higher-level evidence and 50 with moderate-level evidence of affecting salivary glands or causing dry mouth.

The drugs came mostly from medicines for the digestive system, heart and blood vessels, urinary system, nervous system and airways. The table below groups the common ones. The example drugs are taken from the 2017 review's lists, using generic names.

The list isn't complete. The 2017 review notes that it may miss drugs that only cause dry mouth in combination with others, or where dryness hasn't been reported. The ADA also lists GLP-1 receptor agonists, and Cleveland Clinic lists Parkinson's medicines and anti-anxiety drugs. The leaflet that comes with your medicine is worth checking; the NHS suggests looking there to see whether dry mouth is a listed side effect.

For a closer look, the 2017 review found that reduced saliva had been confirmed by actually measuring flow, not just by asking people, for drugs including amitriptyline, fluoxetine, paroxetine, sertraline, clonidine, furosemide, bendroflumethiazide, oxybutynin and tolterodine.

Do over-the-counter medicines count?

Over-the-counter medicines count just as much as prescriptions. Cleveland Clinic says both prescription and over-the-counter medicines can decrease saliva, and it names antihistamines and decongestants among them. These are easy to overlook because people often take them for a few nights at a time without thinking of them as medication.

That matters at bedtime. If you take an allergy tablet or a cold remedy in the evening and wake with a dry mouth, the timing may be the clue. Cleveland Clinic suggests avoiding decongestants and antihistamines when possible if you're prone to dry mouth, so a pharmacist is a good person to ask whether another option would suit you. Tell your doctor and pharmacist about everything you take, including supplements and occasional remedies, so they can see the full picture.

Why do medications make your mouth dry?

Medications make your mouth dry mainly by interfering with the nerve signals that switch on the salivary glands. A 2016 systematic review in Oral Diseases found that drugs can act on the brain, at the junction between nerves and glands, or both, through muscarinic, adrenergic and some other receptors.

The ADA puts it more simply: the most common types of medications causing salivary problems have anticholinergic effects. Anticholinergic drugs block muscarinic receptors, one of the main receptor types the 2016 review identified at the salivary glands. The ADA names tricyclic antidepressants and antihistamines as examples, and Cleveland Clinic lists anticholinergic bladder medicines. Others, such as diuretics, work on the kidneys to remove salt and water from the body, and the 2017 review found measurable drops in saliva with furosemide and bendroflumethiazide.

Some people feel dry without a measurable drop in saliva. The ADA notes that people can experience dry mouth while their saliva flow is within the normal range, so the feeling is real even when a test looks fine.

Does taking several medicines make it worse?

Taking several medicines can raise the risk of dry mouth. The ADA says people taking multiple medications may be at higher risk, and that dry mouth is more common in older adults mainly because of polypharmacy and the conditions that come with age. It estimates dry mouth affects about 30% of people over 65 and up to 40% of those over 80, mostly as a medication side effect.

If you take more than one medicine with dry mouth listed as a side effect, it's worth asking a pharmacist to look at the whole list together rather than one drug at a time.

Why is dry mouth from medication worse at night?

Dry mouth from medication often feels worse at night because your body makes the least saliva while you sleep. The ADA says dry mouth symptoms may worsen at night because salivary output reaches its lowest levels during sleep, and that mouth breathing can make it worse.

So a medicine that leaves you a little dry during the day can leave you parched by 3am, especially if you also sleep with your mouth open or snore. If you wake up dry, it may be worth checking both causes. Our article on why you wake up with a dry mouth covers the others, and mouth breathing and teeth explains why a dry mouth overnight matters for your teeth. If you use a CPAP machine, dry mouth with CPAP is a separate issue with its own fixes.

The other common cause to rule out is a medical condition. Cleveland Clinic lists diabetes, Sjögren's syndrome, stroke and Alzheimer's disease among conditions that can cause dry mouth, and our guide to dry mouth at night and diabetes covers that link.

What should you ask your doctor or pharmacist?

Ask your doctor or pharmacist whether any of your medicines could be behind the dryness, and what can be changed safely. Never stop a medicine yourself. The NHS says not to stop taking a prescribed medicine without getting medical advice first, even if you think it might be causing your symptoms, and Cleveland Clinic says the same.

These are the options the ADA and Cleveland Clinic describe, framed as questions you can bring:

• Could one of my medicines be causing this? Cleveland Clinic suggests asking directly whether you need to change your medications or adjust the dose.
• Is there an alternative in the same class that causes less dryness? The ADA gives the example that SSRI antidepressants tend to cause less dry mouth than tricyclic antidepressants.
• Could I take this medicine earlier in the day? Cleveland Clinic suggests taking medicines that cause dry mouth in the morning rather than at night, and the ADA says daytime dosing of anticholinergic medicines may avoid night-time symptoms.
• Could I take it in divided doses? The ADA says splitting one large dose into smaller ones may reduce dry mouth for some anticholinergic drugs.
• Do I need a prescription treatment? Cleveland Clinic and the ADA list saliva-stimulating prescription medicines for some people with persistent dry mouth.
• How often should I see the dentist? Cleveland Clinic suggests asking this, since dry mouth raises the risk of tooth decay.

Not every option suits every drug. Some medicines need to be taken at a particular time, and some can't be split. That's exactly why the question goes to your prescriber or pharmacist.

What can you do for relief in the meantime?

While you sort out the cause, several simple measures can ease dryness. The NIDCR suggests sipping water, chewing sugarless gum or sucking sugarless hard candy to increase saliva flow, avoiding alcohol and tobacco, limiting caffeine and using a humidifier at night. It also says your provider may suggest artificial saliva or other products to keep your mouth wet.

The NHS adds keeping water by your bed at night, sucking ice cubes, using lip balm and brushing twice a day with an alcohol-free mouthwash, since you're more likely to get tooth decay with a dry mouth. Cleveland Clinic suggests avoiding decongestants and antihistamines when possible and sipping water before swallowing tablets.

If you use a humidifier, the EPA recommends keeping indoor humidity no higher than 50%, using low-mineral water such as distilled water, and cleaning portable units every third day. Our guide to humidifiers for sleep covers this in more detail.

Over-the-counter products help some people, but the evidence is modest. A 2011 Cochrane review of 36 trials found no strong evidence that any topical therapy, such as sprays, gels, lozenges or gum, reliably relieves dry mouth, though chewing gum increased saliva in people whose glands still worked. Our guide to dry mouth products goes through each type, and 10 ways to stop waking up with a dry mouth has more ideas.

When should you see a doctor?

The NHS says to see a GP if dry mouth makes it difficult to talk or eat, is still there after a few weeks of home or pharmacy treatments, affects your sense of taste, or comes with pain, redness, swelling, bleeding or sore white patches. It also says to see a GP if you think a prescribed medicine might be causing it, or if you have other symptoms such as needing to pee a lot or dry eyes.

Read next

• Why do I wake up with a dry mouth?
• Dry mouth products: what helps, and what the evidence shows
• 10 ways to stop waking up with a dry mouth

* This content is for informational and educational purposes only and is not medical advice. It is not intended to diagnose, treat, cure or prevent any disease or health condition. Talk to a qualified healthcare provider about your health.