Summer Heat Can Put You at Risk!
Summer heat and sun may potentially put some medication users and alcohol and/or drug abusers at increased risk. The following summarizes the Health Alert issued by the Cincinnati Drug and Poison Information Center.
Remember! Do not stop taking any prescribed medication without first talking to your doctor.
1. Reactions Due to Increased Heat
The body needs to maintain a relatively consistent temperature to function properly, about 98.6 degrees Fahrenheit. Some medicines can block the body?s natural ability to adjust to changes in temperature. This can result in overheating, which is considered to be a medical emergency.
As the outside temperature increases, the body keeps from overheating by releasing excess heat. The most important ways the body releases heat are by:
- Increasing blood flow to the skin
- Sweating
These two actions work together– increasing blood flow to the skin brings heat to the surface of the body where the skin acts like a large radiator. Sweating increases heat loss from the skin through the process of evaporation.
To increase blood flow to the skin, the blood vessels in the body first inform the brain of the elevated temperature. The brain then sends a message to blood vessels to dilate, increasing blood flow to the skin. The heart must also work harder to circulate the blood.
Some medicines and drugs can disrupt these processes resulting in a reduced ability to adjust to temperature changes. This article will help you learn more about the specific drugs that can harm you by putting you at higher risk for being overheated.
2. Drugs That May Cause Reactions Due to Increased Heat
The body keeps cool by increasing blood flow to the skin and sweating. Listed below are drugs that disturb the body?s natural cooling mechanism and how they may cause you to overheat.
Some drugs reduce blood flow to your skin:
- Certain psychiatric medications (including haloperidol – Haldol®, risperidone – Risperdal®, and others) block the brain’s ability to get the message from the body that the temperature is rising.
- Stimulants and decongestants (including amphetamines, cocaine, pseudoephedrine and phenylephrine) actually reduce blood flow to the skin.
- Certain blood pressure medications (including propranolol and other beta blockers) reduce the ability of the heart to respond to the body’s need to pump more blood to the skin. This may increase the likelihood of dizziness and lightheadedness as the body tries to respond to heat.
Some drugs both increase heat production and decrease blood flow to your skin:
- Recreactional drugs (including amphetamines, MDMA, methamphetamine, PCP, bath salts, and other stimulants)
Some drugs decrease sweating, leading to decreased heat loss and overheating:
- Tricyclic antidepressants (including amitriptyline, nortriptyline)
- Cold and allergy medications (including diphenhydramine – Benadryl®, triprolidine, chlorpheniramine)
- Recreational drugs (including narcotics, Jimson Weed)
Some drugs may cause dehydration:
- These include water pills (including furosemide – Lasix® and hydrochlorothiazide – often listed as HCTZ), alcoholic beverages and products containing caffeine (including coffee or soda pop).
Some medications may cloud your judgment and the need for action:
- Sedatives (including alcoholic beverages, diazepam, alprazolam)
- Opioids (including hydrocodone, oxycodone, morphine, and codeine).
If you are taking any of these medicines or the medicines listed in Table 1 and Table 2 below, be aware that your ability to deal with the heat may be impaired.
Table 1: General Drug Classes That Can Increase the Risk of Heat Injury |
Table 2: Medications with Potential for Hyperthermia (Overheating) or Reduced Heat Tolerance (The generic name is listed first, followed by some of the more common US trade names). Remember! Do not stop taking any prescribed medication without first talking to your doctor Note: This list does not include all medicines that could increase the risk of overheating. |
|
|
3. Overheating Can Be a Medical Emergency
The combination of high heat and high humidity increases the risk of overheating. Physical activity, fluid intake, clothing, outside temperature, and humidity affect your body’s ability to maintain a safe temperature.
Who is at risk for overheating?
- Elderly individuals
- Young children
- People who are isolated
- People of any age living with mental illness
What you can do to avoid overheating:
- Check your medications to see if they may cause overheating.
- Check on elderly loved ones twice daily during the hottest days.
- Never leave children unattended in an automobile.
- Offer fluids frequently to children playing outdoors.
- Wear lightweight clothing.
- Drink plenty of fluids.
- Stay in the shade.
- Avoid heavy activity when it is hot outside.
- When it is hot, move to a cooler area.
- Try to spend some time in air-conditioned spaces like shopping malls.
- Do not exercise or work during the hottest parts of the day.
- Try to plan outdoor activities for the cooler parts of the day.
- Shower frequently.
If you think you are overheated, follow the CDC’s suggestions for treating heat-related illness.
4. Reactions Due to Exposure to the Sun
Some medications may cause patients to burn more easily. This reaction is known as photosensitivity. Sunlight emits ultraviolet A rays. These ultraviolet a rays interact with some medicines to cause a photophotosensitivity reaction.
There are two types of photosensitivity reaction:
- Phototoxicity is the most common form of photosensivity reaction. The interaction lowers the amount of time we can stay in the sun without getting sunburned. The symptoms are similar to sunburn – redness and tenderness of the skin that usually occurs 2 to 6 hours after being out in the sun. The reaction may be severe enough to cause blistering.
- A photoallergic reaction is a less common form of photosensitivity. A photoallergic reaction usually involves itching and scaling of the skin, and generally occurs 5-10 days after exposure to ultraviolet A. The reaction may be severe.
Table 3: Medications and herbs may cause photosensitivity reaction.(Generic name listed first, followed by some of the common trade names) Remember! Do not stop taking any prescribed medication without first talking to your doctor. Note: This list does not include all medicines that could cause photosensitivity reactions. |
|
|
Some plants can also cause photosensitivity reactions. Photosensitivity reactions to plants are similar to those caused by medicines, but are most commonly a result of direct skin contact with sap or juice from the plants followed by exposure to sunlight rather than from eating the plants. The reaction is usually related to chemicals called furocoumarins in the plants. These reactions are most commonly reported in agricultural workers, cooks, bartenders, and grocery store workers, but also may be seen in gardeners and other inadvertently exposed individuals.
Table 4. Plants Associated with Phototoxic Reactions. (Listed as common name followed by the Botanical name) Note: This list does not include all plants that could cause photosensitivity reactions |
5. Preventing Photosensitivity Reactions
Prevention is your best protection against photosensitivity reactions! Be aware of medications that have been associated with this reaction.
- Use protective clothing and sunblock when outdoors.
- Avoid tanning beds to help reduce your risk.
- Use a sunscreen effective against both ultraviolet A and B.
- If you suspect you are having a photosensitivity reaction, seek medical attention right away.
If you have questions regarding any of your medications, contact your physician, a pharmacist who knows you, or your local poison center 1-800-222-1222.
Prepared by Cincinnati Drug and Poison Information Center at (513) 636-5111 or 1-800-222-1222.
For more information:
Go to the Pharmacy and Medications health topic.