Drug Toxicity
Harmful effects from too much of a medication or substance
Quick Facts
- Type: Adverse drug effect / poisoning
- Common causes: Overdose, buildup, drug interactions
- Can affect: Liver, kidneys, heart, brain
- Emergency resource: Call emergency services or Poison Control
Overview
Drug toxicity occurs when the level of a medication or other substance in the body rises high enough to cause harm. This can happen suddenly, as in an overdose, or gradually, when a drug builds up faster than the body can clear it. The effects depend on the specific drug, the dose, and the person's age, organ function, and other medications.
Some toxicity is mild and reversible once the drug is stopped, while severe toxicity can damage the liver, kidneys, heart, or brain and become life-threatening. Toxicity may result from taking too much, from impaired clearance by the liver or kidneys, or from interactions between medications. A suspected overdose is always treated as an emergency.
Symptoms
Symptoms vary widely depending on the drug involved, but warning signs of toxicity can include:
- Nausea, vomiting, abdominal pain, or diarrhea
- Drowsiness, confusion, dizziness, or agitation
- Rapid, slow, or irregular heartbeat
- Fast, slow, or shallow breathing
- Sweating, flushing, or fever
- Tremor, muscle twitching, or seizures
- Yellowing of the skin or eyes (sign of liver injury) or reduced urine output (sign of kidney injury)
A serious overdose is a medical emergency. Trouble breathing, severe drowsiness or unresponsiveness, seizures, chest pain, or a dangerous heartbeat require immediate emergency care.
Causes
Drug toxicity has several common causes:
- Overdose: Taking more than the recommended dose, whether accidental or intentional.
- Drug buildup: Reduced clearance because of liver or kidney problems, so the drug accumulates over time.
- Drug interactions: One medication raising the level or effect of another.
- Narrow safety margin: Some drugs become toxic at levels only slightly above the effective dose and need monitoring.
- Errors: Confusing medications, doubling doses, or dosing mistakes, especially in older adults and children.
Alcohol and recreational drugs can add to the risk of toxicity from prescribed medicines.
Risk Factors
- Older age and taking many medications at once
- Liver or kidney disease that slows drug clearance
- Use of drugs with a narrow safe range, such as certain heart, seizure, or blood-thinning medicines
- Combining medications, supplements, or alcohol
- Confusion about dosing or use of multiple prescribers and pharmacies
- Young children who may accidentally swallow medicines
Diagnosis
Diagnosis combines the history of what was taken with examination and tests to assess severity.
- History: Identifying the substance, amount, timing, and any other drugs or alcohol involved.
- Physical exam: Checking vital signs, level of consciousness, and signs pointing to specific drug effects.
- Blood and urine tests: Measuring drug levels when available, and checking liver, kidney, and electrolyte function.
- Electrocardiogram (ECG): To detect heart rhythm effects of certain drugs.
Poison control centers and toxicology specialists help guide assessment and treatment for many substances.
Treatment
Treatment depends on the substance and severity and ranges from simple observation to intensive care.
- Stopping or adjusting the drug: Discontinuing or lowering the dose of the responsible medication.
- Supportive care: Fluids, oxygen, monitoring, and treatment of breathing, heart, and blood pressure problems.
- Antidotes: Specific reversal agents exist for some drugs, such as for opioid or certain other overdoses, and are given when appropriate.
- Decontamination: In some cases, activated charcoal or other measures may be used soon after ingestion.
- Enhanced elimination: Severe cases may require dialysis or other treatments to remove the substance.
Early contact with emergency services or a poison control center improves outcomes.
Prevention
- Take medications exactly as prescribed and never exceed the recommended dose
- Keep an up-to-date list of all your medicines and supplements, and share it with every prescriber
- Use one pharmacy where possible so interactions can be checked
- Attend recommended blood tests for drugs that need monitoring
- Store all medications safely out of reach of children
- Avoid mixing medicines with alcohol or other drugs unless cleared by a clinician
When to See a Doctor
Call emergency services immediately for a suspected overdose or serious drug toxicity, especially with:
- Trouble breathing or very slow, shallow breathing
- Severe drowsiness, confusion, or unresponsiveness
- Seizures
- Chest pain or a dangerously fast, slow, or irregular heartbeat
In the United States, contact Poison Control for guidance on any suspected poisoning. If the situation may involve self-harm, seek urgent help and treat it as an emergency.
Frequently Asked Questions
What is the difference between drug toxicity and an overdose?
An overdose is one cause of drug toxicity, in which someone takes more of a drug than the body can safely handle at once. Toxicity is the broader harm that results from high drug levels, which can also build up gradually from impaired clearance or drug interactions, not just from a single large dose.
What should I do if I suspect an overdose?
Treat it as an emergency. Call emergency services right away, and in the United States you can also contact Poison Control for immediate guidance. If breathing is slow or the person is unresponsive, having an opioid reversal medicine on hand can be lifesaving for opioid overdoses while help arrives.
Can normal doses of medication cause toxicity?
Yes. Toxicity can occur at usual doses if the liver or kidneys are not clearing the drug well, if another medicine raises its level, or if the drug has a narrow safe range. This is why dose adjustments and monitoring blood tests are sometimes needed.
How can I avoid medication toxicity?
Take medicines exactly as prescribed, keep an up-to-date list of everything you take, use one pharmacy when possible, and attend any recommended monitoring tests. Avoid mixing medicines with alcohol or other drugs without medical advice, and store all medicines safely.
Are there antidotes for drug toxicity?
Specific antidotes exist for some substances, such as opioids and certain other drugs, and are given in emergency settings when appropriate. Many cases, however, are treated with supportive care to protect breathing, the heart, and organ function while the body clears the drug.
References
- MedlinePlus, U.S. National Library of Medicine. Poisoning.
- Centers for Disease Control and Prevention (CDC). Poisoning Prevention.
- U.S. Food and Drug Administration (FDA). Preventable Adverse Drug Reactions.