If these serious side effects occur, stop taking Loniten and refer to a doctor immediately:

• Rapid weight gain of more than 5 pounds, puffiness or swelling in the face, legs, arms or stomach area
• Increase of heart rate, an extra 20 beats per minute when resting
• Trouble breathing
• Severe indigestion, new or worsening pain in the chest, arms, or shoulders
• Dizziness, fainting or lightheadedness

The most common side effect may include:

• Unwanted hair growth
• Darkening of hair

Not all side effects are listed here. Make sure to consult a doctor or healthcare provider before using this medication. Contact a doctor or healthcare provider if side effects are experienced, persist, or worsen. 

Loniten is a medication containing the active ingredient minoxidil, which is indicated for treating high blood pressure. This medication is usually prescribed alongside other medications used to lower blood pressure and comes as an oral tablet.