Early symptoms of PD are subtle and occur gradually. Affected people may feel mild tremors or have difficulty getting out of a chair.  They may notice that they speak too softly or that their handwriting is slow and looks cramped or small. They may lose track of a word or thought, or they may feel tired, irritable, or depressed for no apparent reason. This very early period may last a long time before the more classic and obvious symptoms appear.

Friends or family members may be the first to notice changes in someone with early PD. They may see that the person's face lacks expression and animation (known as "masked face") or that the person does not move an arm or leg normally. They also may notice that the person seems stiff, unsteady, or unusually slow.

As the disease progresses, the shaking or tremor that affects the majority of Parkinson's patients may begin to interfere with daily activities. Patients may not be able to hold utensils steady or they may find that the shaking makes reading a newspaper difficult. Tremor is usually the symptom that causes people to seek medical help.

People with PD often develop a so-called parkinsonian gait that includes a tendency to lean forward, small quick steps as if hurrying forward (called festination), and reduced swinging of the arms. They also may have trouble initiating movement (start hesitation), and they may s suddenly as they walk (freezing).

PD does not affect everyone the same way, and the rate of progression differs among patients.  Tremor is the major symptom for some patients, while for others, tremor is nonexistent or very minor.

PD symptoms often begin on one side of the body.   However, as it progresses, the disease eventually affects both sides.  Even after the disease involves both sides of the body, the symptoms are often less severe on one side than on the other.  The four primary symptoms of PD are:

• Tremor. The tremor associated with PD has a characteristic appearance. Typically, the tremor takes the form of a rhythmic back-and-forth motion at a rate of 4-6 beats per second. It may involve the thumb and forefinger and appear as a "pill rolling" tremor.  Tremor often begins in a hand, although sometimes a foot or the jaw is affected first. It is most obvious when the hand is at rest or when a person is under stress.  For example, the shaking may become more pronounced a few seconds after the hands are rested on a table.  Tremor usually disappears during sleep or improves with intentional movement.
• Rigidity. Rigidity, or a resistance to movement, affects most people with PD. A major principle of body movement is that all muscles have an opposing muscle. Movement is possible not just because one muscle becomes more active, but because the opposing muscle relaxes. In PD, rigidity comes about when, in response to signals from the brain, the delicate balance of opposing muscles is disturbed. The muscles remain constantly tensed and contracted so that the person aches or feels stiff or weak. The rigidity becomes obvious when another person tries to move the patient's arm, which will move only in ratchet-like or short, jerky movements known as "cogwheel" rigidity.
• Bradykinesia. Bradykinesia, or the slowing down and loss of spontaneous and automatic movement, is particularly frustrating because it may make simple tasks somewhat difficult.  The person cannot rapidly perform routine movements. Activities once performed quickly and easily — such as washing or dressing — may take several hours.
• Postural instability. Postural instability, or impaired balance, causes patients to fall easily.  Affected people also may develop a stooped posture in which the head is bowed and the shoulders are drooped. 

A number of other symptoms may accompany PD. Some are minor; others are not. Many can be treated with medication or physical therapy. No one can predict which symptoms will affect an individual patient, and the intensity of the symptoms varies from person to person.

• Depression. This is a common problem and may appear early in the course of the disease, even before other symptoms are noticed. Fortunately, depression usually can be successfully treated with antidepressant medications.
• Emotional changes. Some people with PD become fearful and insecure. Perhaps they fear they cannot cope with new situations. They may not want to travel, go to parties, or socialize with friends. Some lose their motivation and become dependent on family members. Others may become irritable or uncharacteristically pessimistic. 
• Difficulty with swallowing and chewing. Muscles used in swallowing may work less efficiently in later stages of the disease. In these cases, food and saliva may collect in the mouth and back of the throat, which can result in choking or drooling. These problems also may make it difficult to get adequate nutrition.  Speech-language therapists, occupational therapists, and dieticians can often help with these problems.
• Speech changes. About half of all PD patients have problems with speech. They may speak too softly or in a monotone, hesitate before speaking, slur or repeat their words, or speak too fast. A speech therapist may be able to help patients reduce some of these problems.
• Urinary problems or constipation. In some patients, bladder and bowel problems can occur due to the improper functioning of the autonomic nervous system, which is responsible for regulating smooth muscle activity. Some people may become incontinent, while others have trouble urinating. In others, constipation may occur because the intestinal tract operates more slowly. Constipation can also be caused by inactivity, eating a poor diet, or drinking too little fluid. The medications used to treat PD also can contribute to constipation.  It can be a persistent problem and, in rare cases, can be serious enough to require hospitalization.
• Skin problems. In PD, it is common for the skin on the face to become very oily, particularly on the forehead and at the sides of the nose. The scalp may become oily too, resulting in dandruff. In other cases, the skin can become very dry. These problems are also the result of an improperly functioning autonomic nervous system. Standard treatments for skin problems can help. Excessive sweating, another common symptom, is usually controllable with medications used for PD.
• Sleep problems. Sleep problems common in PD include difficulty staying asleep at night, restless sleep, nightmares and emotional dreams, and drowsiness or sudden sleep onset during the day.  Patients with PD should never take over-the-counter sleep aids without consulting their physicians.
• Dementia or other cognitive problems.  Some, but not all, people with PD may develop memory problems and slow thinking.  In some of these cases, cognitive problems become more severe, leading to a condition called Parkinson's dementia late in the course of the disease.  This dementia may affect memory, social judgment, language, reasoning, or other mental skills.  There is currently no way to halt PD dementia, but studies have shown that a drug called rivastigmine may slightly reduce the symptoms.  The drug donepezil also can reduce behavioral symptoms in some people with PD-related dementia.
• Orthostatic hypotension.  Orthostatic hypotension is a sudden drop in blood pressure when a person stands up from a lying-down position. This may cause dizziness, lightheadedness, and, in extreme cases, loss of balance or fainting. Studies have suggested that, in PD, this problem results from a loss of nerve endings in the sympathetic nervous system that controls heart rate, blood pressure, and other automatic functions in the body. The medications used to treat PD also may contribute to this symptom.
• Muscle cramps and dystonia.   The rigidity and lack of normal movement associated with PD often causes muscle cramps, especially in the legs and toes.  Massage, stretching, and applying heat may help with these cramps.  PD also can be associated with dystonia — sustained muscle contractions that cause forced or twisted positions.  Dystonia in PD is often caused by fluctuations in the body's level of dopamine.  It can usually be relieved or reduced by adjusting the person's medications.
• Pain.  Many people with PD develop aching muscles and joints because of the rigidity and abnormal postures often associated with the disease.  Treatment with levodopa and other dopaminergic drugs often alleviates these pains to some extent.  Certain exercises also may help.  People with PD also may develop pain due to compression of nerve roots or dystonia-related muscle spasms.  In rare cases, people with PD may develop unexplained burning, stabbing sensations.  This type of pain, called "central pain," originates in the brain.  Dopaminergic drugs, opiates, antidepressants, and other types of drugs may all be used to treat this type of pain.
• Fatigue and loss of energy.  The unusual demands of living with PD often lead to problems with fatigue, especially late in the day.  Fatigue may be associated with depression or sleep disorders, but it also may result from muscle stress or from overdoing activity when the person feels well.  Fatigue also may result from akinesia – trouble initiating or carrying out movement.  Exercise, good sleep habits, staying mentally active, and not forcing too many activities in a short time may help to alleviate fatigue.

Sexual dysfunction.  PD often causes erectile dysfunction because of its effects on nerve signals from the brain or because of poor blood circulation.  PD-related depression or use of antidepressant medication also may cause decreased sex drive and other problems.  These problems are often treatable.