Psychiatric Medications and Arizona Heat: What to Know

Yes, some psychiatric medications raise the risk of heat illness. CDC guidance for clinicians names lithium, antipsychotics, anticholinergic drugs, certain antidepressants and stimulants, because they can change sweating, thirst, body temperature control or fluid balance (CDC (opens in a new tab)). That does not mean you should stop them. It means an Arizona summer deserves a plan made with your prescriber.

Which psychiatric medications cause heat intolerance?

Your body cools itself mainly by sweating and by sending blood to the skin, and it keeps you drinking by making you thirsty. CDC describes several ways medicines interfere: they can reduce thirst, interfere with the brain’s temperature control, change sweating, deplete fluids or salts, or cause sedation that raises the risk of falls and blunts thirst. It also notes that a dehydrated body clears some drugs more slowly, which matters most for medicines with a narrow margin between a helpful and a harmful level, such as lithium and carbamazepine (CDC (opens in a new tab)).

CDC also lists benzodiazepines, antidepressants and anticonvulsants among drugs that can cause sedation, with more risk of falls and less sense of thirst. The guidance notes that it reflects expert opinion, so it is a map of what to ask about, not a verdict on your medicine. Many of these medicines also carry boxed warnings for other reasons. Antipsychotics, for example, carry one about older adults with dementia-related psychosis (DailyMed (opens in a new tab)), antidepressants about suicidal thoughts in children, teens and young adults (MedlinePlus (opens in a new tab)), and prescription stimulants about misuse and addiction (FDA (opens in a new tab)). Heat is a separate question.

Lithium and heat: why summer needs a plan

Lithium is a mood stabilizer used to treat bipolar I disorder, and the level that helps is close to the level that harms. Its FDA label carries a boxed warning that toxicity is closely tied to blood levels and can occur at doses close to the therapeutic range (FDA label (opens in a new tab)).

Heat matters because lithium and salt travel together through the kidneys. The label says dehydration from long periods of sweating, diarrhea or fever raises the risk of low sodium and lithium toxicity, and that patients should keep a normal diet with salt and stay hydrated (FDA label (opens in a new tab)). Its Medication Guide tells people that if they have been sweating more than usual or have had diarrhea, they may need extra salt and fluids, and to talk to their provider. It lists warning signs of toxicity that include vomiting, diarrhea, drowsiness, weak or twitching muscles, clumsiness, blurred vision, ringing in the ears and an abnormal heartbeat.

Two summer habits deserve a mention. Over-the-counter NSAIDs such as ibuprofen and some water pills can raise lithium levels, so check with your prescriber or pharmacist before using them. And if you are on lithium, ask whether a blood level check makes sense before or during the hottest months. That decision belongs to your prescriber, not to an article. MedlinePlus is plain about it: do not stop taking lithium without talking to your doctor (MedlinePlus (opens in a new tab)).

Antipsychotics, benztropine and the risk of heat stroke

Antipsychotics can disrupt the body’s ability to bring its core temperature down. The olanzapine label, for example, advises care for patients who will be exercising hard, exposed to extreme heat, taking anticholinergic drugs, or dehydrated. It tells patients to call right away if they feel very ill with signs such as sweating too much or not at all, dry mouth, feeling very hot or thirsty, or not being able to pass urine (DailyMed (opens in a new tab)).

The risk can stack. Benztropine, often prescribed to ease antipsychotic side effects, can reduce sweating, and its label says it should be used with caution in hot weather, especially by people who do manual labor in the heat. The label reports that hyperthermia and heat stroke, sometimes fatal, have occurred when drugs like benztropine were combined with phenothiazine antipsychotics or tricyclic antidepressants (DailyMed (opens in a new tab)). Over-the-counter sleep aids with diphenhydramine or doxylamine add to the same load.

Do SSRIs, SNRIs and ADHD medications affect heat tolerance?

They can, usually less dramatically. CDC lists SSRIs such as sertraline and fluoxetine and SNRIs such as duloxetine and venlafaxine as changing sweating, and lists amphetamine and methylphenidate as raising body temperature (CDC (opens in a new tab)). For most people this means paying attention, not avoiding the medicine: drink before you are thirsty and skip the hottest hours for exercise or yard work.

Combinations deserve more care than any single drug. An antidepressant plus an antipsychotic plus a bedtime antihistamine is a different picture from one medicine alone, which is why medication management reviews the whole list.

Heat and mental health in Arizona: what the data show

Heat affects mental health as well as the body. In a study of more than 3.4 million emergency visits by insured U.S. adults, days of extreme heat were linked to 8% higher rates of emergency visits for any mental health condition, including mood, anxiety, substance use and psychotic disorders and self-harm (Nori-Sarma et al., JAMA Psychiatry (opens in a new tab)). An earlier review of heat-wave deaths found that a pre-existing psychiatric illness roughly tripled the risk of dying, while working air conditioning, visiting cool places and more social contact were linked to better outcomes (Bouchama et al. (opens in a new tab)).

Maricopa County’s 2025 report counted 430 heat-related deaths, down from 608 in 2024 and a record 645 in 2023. Substances were involved in 55% of deaths, and 82% of those involved stimulants. About half of the people who died were experiencing homelessness. Among indoor deaths, an air conditioner was present in 94% of cases but not working in 72% of those, and 48% of indoor deaths were found during a welfare check. The report does not count mental illness as its own category, and it does not separate prescribed medicines from other drugs (Maricopa County Department of Public Health (opens in a new tab)).

The county’s enhanced heat surveillance season usually runs from May through October, and in 2025 the largest share of deaths, 37%, came in August. In Arizona, heat planning is a half-year job, not a single heat wave.

How to stay safe in the heat on psychiatric medication

1. 01

   Step 1: Keep taking your medicines as prescribed

   CDC advises clinicians to help patients avoid stopping any medication abruptly without a plan (CDC (opens in a new tab)). Any change on hot days should be individual and made with your prescriber.

2. 02

   Step 2: Ask which of your medicines affect heat

   Bring your full list, including sleep aids, allergy pills and pain relievers. Ask: “Which of these change how I handle heat, and what should I watch for?”

3. 03

   Step 3: Make a hydration plan

   Ask how much fluid is right for you, especially if you take lithium or a water pill, or have heart or kidney disease. Some people need a specific amount, not simply “more.”

4. 04

   Step 4: If you take lithium, ask about summer monitoring

   Ask whether a blood level check before or during summer makes sense, and what to do if you sweat heavily, get a stomach bug or run a fever.

5. 05

   Step 5: Know where to cool off

   Plan for an air conditioner that fails. Maricopa County lists heat relief sites and says you can call 2-1-1 to find one that is open (Maricopa County (opens in a new tab)).

6. 06

   Step 6: Set up a check-in

   Agree that a friend or family member will check on you during extreme heat, especially if you live alone. Welfare checks found nearly half of Maricopa County’s indoor heat deaths in 2025.

Heat exhaustion vs heat stroke: warning signs and when to call 911

CDC lists heat exhaustion signs as heavy sweating, cold, pale and clammy skin, a fast weak pulse, nausea or vomiting, muscle cramps, tiredness or weakness, dizziness, headache and fainting. Move to a cool place, loosen clothes, use cool wet cloths and sip water. Get medical help right away if you are throwing up, symptoms get worse, or they last longer than an hour (CDC (opens in a new tab)).

Video · 1:37 · Mayo ClinicHow extreme heat and humidity affect your health

Can heat damage your medications?

Yes, some medicines lose effectiveness when stored badly. CDC advises clinicians to counsel patients not to leave medications in a car or other places that can get very hot (CDC (opens in a new tab)). The FDA recommends storing most medicines in a cool, dry place such as a dresser drawer, keeping them away from hot appliances, and reading the label for specific instructions (FDA (opens in a new tab)).

In Arizona, that includes mail-order refills left in a metal mailbox or on a sunny porch. Bring deliveries in promptly, and if a medicine looks or smells different, ask a pharmacist before taking it.

Getting a medication review before next summer

Heat is one of many physical factors that shape how you feel and how medicines work. The articles on integrative psychiatry and physical causes of anxiety, depression and ADHD symptoms explain that approach.

With medication management, Dr. Justin Schwarting, DNP, PMHNP-BC, reviews each medication for what it is for and whether it still earns its place, orders lab work when it could change the plan, and makes changes one at a time. Follow-ups are 30 minutes ($120 self-pay) by video anywhere in Arizona. For questions about lab timing for lithium, ask us. When you are ready, request an appointment.