Synalgos-DC Side Effects
Generic name: aspirin / caffeine / dihydrocodeine
Medically reviewed by Drugs.com. Last updated on Jul 4, 2022.
Note: This document contains side effect information about aspirin / caffeine / dihydrocodeine. Some of the dosage forms listed on this page may not apply to the brand name Synalgos-DC.
For the Consumer
Applies to aspirin/caffeine/dihydrocodeine: oral capsule
- This drug is a strong pain drug that can put you at risk for addiction, abuse, and misuse. Misuse or abuse of this drug can lead to overdose and death. Talk with your doctor.
- You will be watched closely to make sure you do not misuse, abuse, or become addicted to this drug.
- This drug may cause very bad and sometimes deadly breathing problems. Call your doctor right away if you have slow, shallow, or trouble breathing.
- The chance of very bad and sometimes deadly breathing problems may be greater when you first start this drug or anytime your dose is raised.
- Even one dose of this drug may be deadly if it is taken by someone else or by accident, especially in children. If this drug is taken by someone else or by accident, get medical help right away.
- Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
- This drug has an opioid drug in it. Severe side effects have happened when opioid drugs were used with benzodiazepines or other drugs that may make you drowsy or slow your actions. This includes slow or troubled breathing and death. Benzodiazepines include drugs like alprazolam, diazepam, and lorazepam. Benzodiazepines may be used to treat many health problems like anxiety, trouble sleeping, or seizures. If you have questions, talk with your doctor.
- Many drugs interact with this drug and can raise the chance of side effects like deadly breathing problems. Talk with your doctor and pharmacist to make sure it is safe to use this drug with all of your drugs.
- Do not take with alcohol or products that have alcohol. Unsafe and sometimes deadly effects may happen.
- Get medical help right away if you feel very sleepy, very dizzy, or if you pass out. Caregivers or others need to get medical help right away if the patient does not respond, does not answer or react like normal, or will not wake up.
- Using this drug for a long time during pregnancy may lead to withdrawal in the newborn baby. This can be life-threatening. Talk with the doctor.
- This drug is not approved for use in children. Do not give to a child younger than 12 years of age. Children between 12 and 18 years of age who are very overweight or have certain other health problems like sleep apnea or other lung or breathing problems must not use this drug. If your child has been given this drug, ask the doctor for information about the benefits and risks.
- Some children have had very bad and sometimes deadly breathing problems when using codeine after surgery to remove tonsils or adenoids. Do not give to a child younger than 18 years of age who has had surgery to remove tonsils or adenoids. Talk with your child's doctor.
What are some side effects that I need to call my doctor about right away?
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.
- Signs of high potassium levels like a heartbeat that does not feel normal; feeling confused; feeling weak, lightheaded, or dizzy; feeling like passing out; numbness or tingling; or shortness of breath.
- Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
- Very bad dizziness or passing out.
- Trouble breathing, slow breathing, or shallow breathing.
- Noisy breathing.
- Feeling very sleepy.
- Feeling confused.
- Chest pain or pressure or a fast heartbeat.
- Very bad belly pain.
- Very bad constipation.
- Feeling very tired or weak.
- Any unexplained bruising or bleeding.
- Ringing in ears.
- Hearing loss.
- Mood changes.
- A severe and sometimes deadly problem called serotonin syndrome may happen if you take this drug with certain other drugs. Call your doctor right away if you have agitation; change in balance; confusion; hallucinations; fever; fast or abnormal heartbeat; flushing; muscle twitching or stiffness; seizures; shivering or shaking; sweating a lot; severe diarrhea, upset stomach, or throwing up; or severe headache.
What are some other side effects of this drug?
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
- Feeling sleepy.
- Upset stomach or throwing up.
- Feeling tired or weak.
- Stomach pain.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.
For Healthcare Professionals
The most frequently expected adverse reactions based on the individual components include lightheadedness, dizziness, drowsiness, sedation, nausea, vomiting, constipation, pruritus and skin reactions.[Ref]
Frequency not reported: Diarrhea, nausea, stomach pain, vomiting[Ref]
Frequency not reported: Anaphylactoid reactions, hypersensitivity reactions[Ref]
Frequency not reported: Confusion, physical and psychological dependence, hallucinations vivid dreams
Frequency not reported: Sweating, pruritus, skin reactions
Frequency not reported: Orthostatic hypotension
Chronic opioid use may influence the hypothalamic-pituitary-gonadal axis and lead to androgen deficiency; however, the causal role of opioids is unknown due to the lack of studies into the many medical, physical, lifestyle, and psychological stressors that influence gonadal hormone levels.[Ref]
Frequency not reported: Anorexia[Ref]
Rare (less than 0.1%): Narcosis
Frequency not reported: Lightheadedness, dizziness, drowsiness, sedation, headache
Frequency not reported: Headaches, lightheadedness, tremor
Frequency not reported: Serotonin syndrome[Ref]
Frequency not reported: Miosis
Frequency not reported: Scintillating scotoma[Ref]
Frequency not reported: Fatigue
Rare (less than 0.1%): Acute renal failure
Frequency not reported: Granulomatous interstitial nephritis
Frequency not reported: Diuresis[Ref]
More about Synalgos-DC (aspirin / caffeine / dihydrocodeine)
- Drug interactions
- Dosage information
- During pregnancy
- Reviews (1)
- Drug images
- Drug class: narcotic analgesic combinations
Related treatment guides
1. "Product Information. Trezix (acetaminophen/caffeine/dihydrocodeine)." WraSer Pharmaceuticals (2016):
2. "Product Information. Synalgos-DC (aspirin / caffeine / dihydrocodeine)." Sun Pharmaceutical Industries (2022):
3. US Food and Drug Administration "Opioid Pain Medicines: Drug Safety Communication - New Safety Warnings Added to Prescription Opioid Medications. http://www.fda.gov/safety/medwatch/safetyinformation/safetyalertsforhumanmedicalproducts/ucm491715.htm." (2016):
Some side effects may not be reported. You may report them to the FDA.