Opioid Side Effects: Short-term and Long-term Impact on the Body

Constipation is a common complaint, but the effects are wide-ranging and can be severe.

Like any drug, prescription or not, opioids come with a list of possible side effects. The difference is that opioids, unlike most other meds people take, can be highly addictive. And that can lead to potential misuse or even overdose, says the Substance Abuse and Mental Health Services Administration.

However, if your doctor believes a short course of an opioid drug may be useful for treating your pain, you'll want to make an informed decision about whether to take these drugs and for how long. Knowing the side effects of opioids can help you weigh the benefits and risks.

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What Types of Opioids Can Cause Side Effects?

In order to understand opioid side effects, it's vital to get a quick background on these drugs. Certain opioids are prescribed to treat moderate-to-severe pain. Others are produced illegally and sold on the street for the high they produce.

Prescription opioids

This category includes natural opioids, such as morphine and codeine, and semi-synthetic opioids, including oxycodone, hydrocodone, and oxymorphone. It also includes synthetic opioids, like fentanyl, which goes by brand names Actiq, Duragesic, and Sublimaze.

Fentanyl is highly potent—50 to 100 times more than morphine, reports the National Institute on Drug Abuse (NIDA). Prescription opioids can produce a euphoric feeling that can be addictive, but these drugs are generally safe when taken for a short period of time and under a doctor's direction, says the CDC.

Illegal opioids

This category includes heroin, a drug made from morphine that can be smoked, sniffed, injected, or snorted. Heroin quickly binds to opioid receptors responsible for pain, pleasure, heart rate, breathing, and more, says NIDA. Illegally produced fentanyl may be sold as a powder, nasal spray, or pill, and its effects on the body are similar to other opioid painkillers, but it also poses a high risk of overdose, says the US Drug Enforcement Agency.

Opioids can bring far more than a feeling of euphoria. First, there's the risk of overdose. In 2019, nearly 50,000 Americans died of drug overdoses in which opioids were involved, according to the CDC Injury Center.

On top of the risk of overdose, opioid side effects are wide-ranging.

Side Effects of Short-term Use

Side effects of opioid use vary tremendously depending on the person and length and quantity of use. However, there are a few general opioid side effects to know.

According to Ashley McGee, RN, the vice president of nursing at Mountainside, a New York, New Jersey, and Connecticut provider of drug addiction treatment, the short-term side effects of opioid use can include:

  • Nausea
  • Decreased respiratory rate
  • Unconsciousness
  • Increased drowsiness
  • Pinpoint pupils
  • Constipation

In some instances, these side effects will require an additional treatment plan. Harvard Health Publishing reports that constipation occurs in 41% of people using them for chronic noncancerous pain and in 94% of people using them for cancer-related pain

"Oftentimes, doctors who prescribe opioids to patients for pain management will also prescribe or recommend laxatives at the start of the opioid prescription," Angela L. Robinson, LPCMH, NCC, the clinical director at NorthNode Group Counseling in Dover, Delaware, tells Health. She has had patients stop taking opioids due to constipation causing intense pain and discomfort.

More potent opioids, like fentanyl and heroin, may have more severe side effects.

According to the National Institute on Drug Abuse, fentanyl's side effects include:

  • Drowsiness
  • Nausea
  • Constipation
  • Confusion
  • Breathing problems

Then there's heroin. NIDA says the short-term side effects include:

  • Moving in and out of consciousness
  • Dry mouth
  • Flushed skin
  • Heavy limbs
  • Nausea
  • Vomiting
  • Severe itching

Side Effects of Long-term Use

Chronic opioid use can produce additional side effects. According to the NIDA, the side effects of long-term heroin use can be extensive and include:

  • Insomnia
  • Collapsed veins
  • Damaged nose tissue
  • Constipation
  • Stomach cramping
  • Liver and kidney disease
  • Pneumonia
  • Depression
  • Sexual dysfunction
  • Irregular menstrual cycles
  • Withdrawal symptoms

"In addition to gastrointestinal complications and drowsiness, long-term side effects of opioid use change a person's behavior to hyper-fixate on opioids and their next dosage," explains Robinson. "A person experiences pain in a different way, and the body becomes more hypersensitive to pain because of pain suppression and the loss of the naturally built-up tolerance."

Damioli adds that it is critical for people using opioids long-term to also engage in non-opioid-related pain management—otherwise, the increased sensitivity can make their pain worse over time. He also cautions that constipation can continue and become more severe with long-term use.

Opioid Withdrawal

Due to their incredibly addictive nature, a person can experience opioid withdrawal very quickly. In fact, Mayo Clinic reports that after only five days of opioid use, the likelihood of someone becoming dependent on opioids increases significantly.

According to the US National Library of Medicine, side effects of opioid withdrawal include:

  • Agitation
  • Muscle pain
  • Yawning
  • Insomnia
  • Anxiety
  • Nausea
  • Vomiting
  • Stomach cramps

"Symptoms will lessen over time, but every person is different as to how they tolerate withdrawal," says McGee. "Some individuals can also experience post-acute withdrawal, the delayed onset of withdrawal symptoms after completing a detox of a substance. These symptoms are generally not as severe but are just more prolonged."

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Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Substance Abuse and Mental Health Services Administration (SAMHSA). Opioids.

  2. National Institute on Drug Abuse. Fentanyl drugfacts.

  3. Centers for Disease Control and Prevention (CDC). Commonly used terms: opioids.

  4. National Institute on Drug Abuse. Heroin drugfacts.

  5. United States Drug Enforcement Administration (DEA). Facts about fentanyl.

  6. Centers for Disease Control and Prevention (CDC). Injury Center. Death rate maps & graphs: drug overdose.

  7. Harvard Health. Common causes of constipation.

  8. Mayo Clinic. What are opioids and why are they dangerous?.

  9. MedlinePlus Medical Encyclopedia. Opiate and opioid withdrawal.

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