Get emergency medical help if you have any of these signs of an allergic reaction to Singulair: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have a serious side effect such as:
- skin rash, bruising, severe tingling, numbness, pain, muscle weakness;
- mood or behavior changes, anxiety, depression, or thoughts about suicide or hurting yourself;
- tremors or shaking;
- easy bruising, unusual bleeding (nose, mouth, vagina, or rectum), purple or red pinpoint spots under your skin;
- severe sinus pain, swelling, or irritation;
- worsening asthma symptoms; or
- severe skin reaction - fever, sore throat, swelling in your face or tongue, burning in your eyes, skin pain, followed by a red or purple skin rash that spreads (especially in the face or upper body) and causes blistering and peeling.
Less serious Singulair side effects may include:
- stomach pain, heartburn, upset stomach, nausea, diarrhea;
- tooth pain;
- tired feeling;
- fever, stuffy nose, sore throat, cough, hoarseness; or
- mild rash.
This is not a complete list of side effects and others may occur.