See also Warning section.

Before taking this medication, tell your doctor or pharmacist if you are allergic to promethazine or to dextromethorphan; or to any other phenothiazines (such as prochlorperazine); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: breathing problems (such as asthma, emphysema, sleep apnea), heart problems (such as slow/irregular heartbeat, chest pain), liver problems, difficulty urinating (such as due to an enlarged prostate), stomach/bowel problems (such as blockage, ulcer), high blood pressure, diabetes, a certain eye problem (glaucoma), seizures, blood/immune system problems (such as bone marrow depression).

This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Children should be supervised during bicycle riding and other possibly hazardous activities to avoid injury. Limit alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.

Liquid forms of this medication may contain sugar, alcohol, or aspartame. Caution is advised if you have diabetes, liver disease, phenylketonuria (PKU), or any other condition that requires you to limit/avoid these substances in your diet. Ask your doctor or pharmacist about using this product safely.

Before having surgery or procedures such as X-rays with dye, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Children may be more sensitive to the side effects of this drug, especially slowed breathing and uncontrolled movements (see also Warning section). Children may also experience excitability rather than drowsiness. Special caution should be taken in children with a family history of sudden infant death syndrome (SIDS), those who have a severe loss of fluid (dehydration), and those who are hard to wake up from sleep.

Older adults may be more sensitive to the side effects of this drug, especially drowsiness, confusion, constipation, or trouble urinating. Drowsiness and confusion can increase the risk of falling.

During pregnancy, this medication should be used only if clearly needed. Discuss the risks and benefits with your doctor.

It is unknown if this medication passes into breast milk. However, it may have undesirable effects on a nursing infant. Consult your doctor before breastfeeding.